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In the treatment of papillary thyroid carcinoma (PTC), supplementary lymph node dissection (LND) is not well standardized. The purpose of this study was to evaluate the significance of the cervical compartments in the lymphatic spread of PTC and the impact of modified radical neck dissection (MRND) as an additional surgical procedure to thyroid resection. From 1999 to 2002, LND of the central compartment (compartment A) was performed in 39 patients. Among this group, additional MRND of the ipsilateral compartment (compartment B) and the contralateral compartment (compartment C) was performed in 29 and 15 patients respectively, who met the selection criteria. The mean number of nodes resected was 11 (5-22) in compartment A, 23 (8-37) in compartment B, and 22 (10-31) in compartment C. Histopathologic findings revealed node invasion of compartment A in 25 patients (64.1%), of A and B in 20 patients (51,2%) and of A, B, and C in 13 patients (33.3%). From the 25 patients with metastases in compartment A, 80% (20 patients) already had metastases in compartment B and 52% (13 patients) had metastases in all three compartments. All patients free of metastasis (M0) in compartment A were also metastasis free in both lateral compartments. Postoperative whole-body scanning I(131) in M0 patients showed no uptake at all. Mapping of the cervical anatomy in compartments seems to be a useful taxonomy for clarifying the lymphatic spread of PTC. Patients having PTC without metastasis in compartment A are almost certainly disease free at the time of operation. Lymph node metastasis in the central compartment appears to be a valuable indicator of lymphatic invasion of the lateral compartment and a strong indication for performance of a unilateral or bilateral MRND to complete the surgical removal of tumor.
OBJECTIVE: A prospective descriptive study to determine the value of magnetic resonance imaging (MRI) as an aid in diagnosing (chronic) exertional compartment syndrome. DESIGN AND PATIENTS: MRI was performed in 21 patients (41 anterior compartments) with chronic compartment syndrome at rest and following physical exercise. Median (T2-weighted) signal intensity on the MRI scan was determined in the anterior and the (superficial) posterior compartment of the lower leg before and after exercise. Postexercise increases in the signal intensity in these two compartments were compared. After fasciotomy, a second MRI scan was performed in 13 patients (25 anterior compartments) on the basis of the same protocol. MR studies were performed in 12 normal controls (24 anterior muscle compartments) on the basis of the same protocol. RESULTS: T2-weighted signal intensity increased by 27.5% (range 13.6-38.6%) following exercise in the anterior compartment of patients with a chronic compartment syndrome. In the posterior compartment this increase amounted to 4.25% (range 0-10.2%). Following fasciotomy, the increase in the anterior compartment was 4.1% (range 1.0-5.2%), while the increase in the posterior compartment amounted to 5.6% (range 0-11.0%), In normal controls, the increase in the anterior compartment was 7.6% (range 0-9. 1%), while in the posterior compartment it was 4.0% (range 0-7.2%). CONCLUSIONS: In patients with a chronic compartment syndrome, the affected (anterior) compartment shows a statistically significant increase in (T2-weighted) signal intensity during exercise compared with both the (superficial) posterior compartment and the anterior compartment of normal controls. This effect disappeared after fasciotomy. In view of the substantial increase in T2-weighted signal intensity, MRI can be used in diagnosing chronic compartment syndrome.
Compartment syndrome is a limb-threatening and occasionally life-threatening injury. It occurs whenever the tissue pressure (referred to as interstitial pressure) within a closed anatomic space is greater than the perfusion pressure. Untreated, compartment syndrome leads to tissue necrosis, permanent functional impairment and, if severe in large compartments, renal failure and death. Compartment syndrome can occur within any muscle group located in a compartment. It is most common following an event that severely damages a muscle, like a crushing or twisting injury. Mechanisms of injury that involve circumferential burns, ischemia and tourniquets can cause compartment syndrome. Motorcyclists who suffer lower-extermity injuries in accidents are a high-risk group. A tough membrane referred to as a fascia covers muscle groups, forming a compartment for the muscle. In normal circumstances, this arrangement allows the muscle to function more efficiently, but if the muscle is injured in any way, the fascia limits the amount of swelling that can occur. This in turn restricts the flow of blood through the affected region. The first compromised function within the compartment is the flow of lymph and venous blood. If there are sensory nerves running through the compartment, they will not function correctly, causing the numbness, tingling and, later, the pain associated with compartment syndrome. With more swelling, arterial flow is compromised, pain worsens and motor function is impaired. An artificial way of producing a compartment syndrome is to place a cast or splint around a damaged extermity, compressing it. This is a way emergency personnel can compromise an injury and cause long-term consequences for the patient. Recovery is achieved by surgically opening the compartment involved (a fasciotomy) and releasing the pressure. The muscle at first will swell outside the compartment, but then it recovers, swelling is reduced and normal function can be recovered. Prehospital treatment of extremity injuries that will prevent or limit compartment syndrome is immobilization, elevation and cooling. Recognition of the syndrome later in its course, as in this case, requires the EMT to remove the patient to an appropriate emergency department. Prehospital providers need to recognize that many mechanisms of injury can produce this syndrome, even those that seem relatively minor. All injured patients should be educated to seek care should the symptoms of numbness, deep pain and coolness to the distal extremity occur. This case involved a patient who, from a relatively minor mechanism of trauma, experienced an internal disruption of the muscle group controlling the thumb (thenar mass). The early swelling in the thenar compartment resulted in the patient experiencing a tingling sensation in his left thumb. In many cases, such an injury would be referred to as a "stinger" (a temporary neurological deficit due to a sudden and excessive stimulation of a neurologic plexus or junction). But this patient had more swelling in the compartment, resulting in a lack of circulation manifested by a cool extremity, poor capillary refill and decreased pulse oximetry. Luckily, this officer recognized the need for medical evaluation of what appeared to be a minor injury and was returned to duty with no permanent impairment.
Bacterial community structure and the predominant nitrifying activities and populations in each compartment of a three-compartment activated sludge system were determined. Each compartment was originally inoculated with the same activated sludge community entrapped in polyethylene glycol gel granules, and ammonium nitrogen was supplied to the system in an inorganic salts solution at a rate of 5.0 g of N liter of granular activated sludge-1 day-1. After 150 days of operation, the system was found to comprise a series of sequential nitrifying reactions (K. Noto, T. Ogasawara, Y. Suwa, and T. Sumino, Water Res. 32:769-773, 1998), presumably mediated by different bacterial populations. Activity data showed that all NH4-N was completely oxidized in compartments one and two (approximately half in each), but no significant nitrite oxidation was observed in these compartments. In contrast, all available nitrite was oxidized to nitrate in compartment three. To study the microbial populations and communities in this system, total bacterial DNA isolated from each compartment was analyzed for community structure based on the G+C contents of the component populations. Compartment one showed dominant populations having 50 and 67% G+C contents. Compartment two was similar in structure to compartment one. The bacterial community in compartment three had dominant populations with 62 and 67% G+C contents and retained the 50% G+C content population only at a greatly diminished level. The 50% G+C content population from compartment one hybridized strongly with amo (ammonia monooxygenase) and hao (hydroxylamine oxidoreductase) gene probes from Nitrosomonas europaea. However, the 50% G+C content population from compartment two hybridized strongly with the hao probe but only weakly with the amo probe, suggesting that the predominant ammonia-oxidizing populations in compartments one and two might be different. Since different activities and populations come to dominate in each compartment from an identical inoculum, it appears that the nitrification processes may be somewhat incompatible, resulting in a series of sequential reactions and different communities in this three-compartment system.
Three patients with calcaneal fractures developed clawing of the lesser toes as a late sequela. Believing that this complication may be the result of contractures from an occult compartment syndrome of the foot, an investigation of the anatomical compartments of the foot was performed. The various compartments of 17 unembalmed adult lower limb specimens were injected with dyed gelatin in a controlled fashion. After freezing, the feet were sectioned either transversely or sagittally. The distribution of the dyed gelatin was then studied. Nine compartments were identified. These were the (1) medial, (2) superficial, (3) lateral, (4) adductor, (5-8) four interossei, and (9) calcaneal. The contents of each compartment was then studied as was the compartment's location in the foot and its position relative to other compartments. We identified a new, separate compartment which lies deep to the superficial compartment in the hindfoot area only. This compartment contains the quadratus plantae muscle. We have named it the "calcaneal" compartment to emphasize its hindfoot location. In addition, a communication was demonstrated between the calcaneal compartment and the deep posterior compartment of the leg through the retinaculum behind the medial malleolus, following the neurovascular and tendinous structures. Claw toe deformity following calcaneus fracture appears to be due to late contracture of the quadratus plantae muscle in the calcaneal compartment. A surgical technique for release of all of the foot compartments is described.
BACKGROUND: Changes in compartment pressures have been noted during traction, reduction, and intramedullary fixation of fractures. Changes in limb length and compartment volumes are suspected contributing factors. Pressure and volume changes are known to be related in animal models. If an acute increase in limb length can adversely affect compartment pressures, reversal or delay of such an increase in length may be of value in the treatment and prevention of compartment syndromes. METHODS: A clinical example is presented in which a documented anterior compartment syndrome was successfully treated by deliberate loss of fracture reduction, without fasciotomy. Fracture reduction was later restored when swelling subsided. Anterior compartment pressures were recorded in response to limb length changes in osteotomized cadaver limbs stabilized with external fixation. RESULTS: The pressure in the anterior compartment varies directly with acute changes in the length of the leg, in an experimental model. Mathematical analysis indicates that available volume within a compartment varies inversely with acute changes in its length. CONCLUSIONS: Fracture reduction that restores the length of an acutely injured extremity may increase pressure in the compartments by decreasing available volume. Deliberate loss of reduction can decrease pressure in the compartments, offering a potential alternative to fasciotomy in the care of compartment syndrome in cautiously selected, monitored patients. Early stabilization without reduction, followed by delayed reduction, may be preferable during treatment of fractures prone to compartment syndrome. Decreased available compartment volume may contribute to compartment syndrome after distraction with intramedullary rods or skeletal traction.
The P wave in the surface ECG represents atrial electrical activation and may be altered in certain pathological conditions. Atrial compartment operation has been used to convert chronic AF to sinus rhythm. However, this procedure may result in changes of impulse conduction in various atrial compartments and alters the P wave morphology. This study sought to elucidate the P wave changes after the atrial compartment operation for AF. Fifteen patients undergoing the atrial compartment operation for chronic AF were studied. In the operation, the atrium was divided into three compartments, namely the left atrium, the atrial septum including sinus and AV nodes, and the right atrial compartment. The anatomic connection between adjacent compartments were preserved at the posterior lower margin of incisions. The surface lead P waves were correlated with intracardiac recording and stimulation in various atrial compartments. Fifteen age- and sex-matched control patients without structural heart diseases were compared. The results showed that patients undergoing the atrial compartment operation had a prolonged P wave duration (190 +/- 27 v s95 +/- 14 ms, P < 0.001), a prolonged PR interval (207 +/- 23 vs 155 +/- 20 ms, P < 0.001), and a shortened PR segment (17 +/- 19 vs 60 +/- 17 ms, P < 0.001). The increase in P wave duration was primarily due to a conduction delay from the sinus node to the other atrial compartments as the conduction time from the high right atrium to the right atrial appendage was 132 +/- 57 ms(vs 21 +/- 6 ms for control,P < 0.001), and the conduction time from the high right atrium to the distal coronary sinus was 140 +/- 55 ms(vs 70 +/- 15 ms, P < 0.001). However, the conduction from the high right atrium to the low septal right atrium, which were located in the same compartment, was not impaired. Also, the conduction in the AV node and His-Purkinje system were not impaired. The mean axis of P waves varied greatly, but was not statistically different from that of the control group (60 +/- 48 degrees vs 52 +/- 18 degrees,P > 0.05). Although the patients undergoing atrial compartment operation had a larger left atrial size, their P wave amplitude was smaller (1.0 +/- 0.3 vs 1.3 +/- 0.3 mm, P < 0.01), and an increased negative terminal force in V1 was not seen (0.02 +/- 0.02 vs 0.02 +/- 0.01 mm/s, P > 0.05). Alteration in P wave morphology was seen in 14 patients. All the P waves showed a biphasic configuration with an initial positive and a terminal slurred negative deflection in leads II, III, and aVF. The terminal components represented the activation of right atrial appendage in 5 patients, the left atrium in 1, and the combined activation of right atrial appendage and the left atrium in 8 patients. The P wave morphology suggested that activation of both the right atrial appendage and the left atrial compartments proceeded in a caudocranial direction as a result of the atrial incisions. In conclusion, atrial compartment operation altered the conduction time and direction in the atria and resulted in characteristic P wave changes.
1. The basic assumptions involved in one- and two-compartment models with age-independent distributed residence times (exponential, G1) for describing digesta flow are reviewed as the bases for describing families of one- and two-compartment models which assume age-dependent distributions (Gn) of residence times. 2. The two-compartment, age-independent model with exponentially distributed residence times (G1G1) yielded estimates of essentially equal rate parameters when fitted to faecal values for all four cows receiving a diet of 500 g coarsely chopped, sodium hydroxide-treated straw/kg and one of four cows receiving the same diet but with ground and pelleted straw. The incorporation of progressively higher orders of age dependency (G2-G6, Gn) into the faster turnover compartment of two-compartment models (GnG1) resulted in a resolution of equal rate parameters estimated by the G1G1 model and a reduction in standard errors for the rate and the initial concentration parameters. 3. The occurrence of equal rate parameters in two-compartment models indicated an age-dependent process; a process which could equally well be described by a one-compartment, age-dependent compartment having an order of age dependency equal to the sum of these orders in the two-compartment model with equal rate parameters. 4. The age-independent models overestimated time of first appearance in the faeces of a meal's particles. The association of age dependency with the faster turnover compartment resulted in earlier estimates for first appearance of the marked particles; estimates which were more consistent with observed first appearance. 5. The faecal excretion pattern from cows fed on the ground and pelleted straw diet exhibited an age-independent distribution of longer residence times which dominated approximately 80% of the later residence times. Age-dependent, one-compartment models gave a poor fit to such data from these cows fed on ground and pelleted straw. In contrast, age-dependent, one-compartment models provided an excellent fit to data from cows fed on chopped straw; data which indicated that age-independent distributions of residence times were much delayed in appearing or were totally absent. 6. The mean residence time for the slower turnover, age-independent compartment estimated from faecal excretional of stained particles from either diet was similar to that estimated from duodenal concentrations of the stained particles. This suggests that the slower turnover model compartment was confined to preduodenal sites.(ABSTRACT TRUNCATED AT 250 WORDS)
AIMS: Surgical treatment for atrial fibrillation is now feasible in selective cases. The aim of this study was to assess the electrophysiological properties of patients undergoing atrial compartment operation for chronic atrial fibrillation. METHODS AND RESULTS: Electrophysiological studies were performed in 20 mitral valve patients with atrial fibrillation who had been maintained in sinus rhythm for more than 1 year after atrial compartment operation. Intra-cardiac recording and programmed electrical stimulation were performed in various atrial compartments. The parameters studied included sinus node function, atrial conduction and refractoriness, atrioventricular conduction function and inducible arrhythmias if any. Intra-cardiac recordings showed that the rhythm was of sinus origin in all cases, with the earliest atrial activity located in the high right atrium. The mean sinus cycle length was 750 +/- 110 ms, AH time 106 +/- 29 ms, and HV time 53 +/- 7 ms. The sinus node function was normal in 18 patients (90%), and only two patients had prolonged sinus node recovery and sino-atrial conduction. The right atrial appendage compartment was driven by the sinus node in all patients. However, the conduction time from the high right atrium to the right atrial appendage compartment was markedly prolonged in 12 of 15 patients (80%) undergoing the three-compartment operation in which an incision was placed between the high right atrium and right atrial appendage compartments. On the other hand, the electrical activities in the left atrial compartment were much more varied. In 13 of 20 patients (65%), the left atrial compartment was driven by the sinus node; 11 of the 13 patients had a normal or mildly prolonged conduction time (ranged 75 to 146 ms), whereas two patients had a marked delay in conduction (200 ms and 266 ms, respectively). In the remaining seven patients, the left atrial compartments were dissociated from the rest of the heart; five of them had a quiescent left atrium, one a fluttering left atrial rhythm, and one a slow left atrial rhythm. The effective refractory period was longer in the left atrial compartment (242 +/- 47 ms) as compared to that of the high right atrium (224 +/- 26 ms, P < 0.01) and right atrial appendage compartments (219 +/- 25 ms, P < 0.01). Programmed electrical stimulation could not induce atrial fibrillation in any patient, whereas two patients had inducible atrial flutter and three repetitive atrial responses. CONCLUSIONS: (1) Atrial compartment operation does not impair sinus node function in most cases. (2) Elimination of atrial fibrillation while maintaining the electrical connection between different atrial compartments is feasible.
OBJECTIVE: To present the case of a college football player with acute, atraumatic, exercise-induced compartment syndrome in the leg. BACKGROUND: Acute, atraumatic, exercise-induced compartment syndrome is an infrequently reported cause of leg pain in the athlete. If left untreated, acute compartment syndrome can cause muscle necrosis. DIFFERENTIAL DIAGNOSIS: Chronic exertional compartment syndrome, medial tibial syndrome, stress fracture. TREATMENT: Treatment consists of compartment fasciotomy. UNIQUENESS: This previously healthy, but unconditioned, athlete developed severe anterolateral left leg pain after two days of fall practice in which he was unable to run a mile in 7.5 minutes. Physical examination by the team physician revealed acute compartment syndrome, and an emergency anterolateral compartment fasciotomy was performed. Second-look débridement performed 48 hours later revealed no significant change in the necrotic appearance of the anterior compartment soft tissue. Therefore, the dead muscle was completely débrided, and a free-flap latissumus dorsi graft was used for coverage of the wound. With recovery, strength returned to normal in the lateral compartment but remained 0/5 in the anterior compartment. The patient had persistent sensory loss in the distributions of the superficial and deep peroneal nerves. CONCLUSIONS: Although much less common than the more frequent causes of leg pain (ie, chronic exertional compartment syndrome, medial tibial syndrome, stress fracture), acute compartment syndrome is potentially more devastating. When the increased intracompartmental pressure within a closed tissue space exceeds capillary perfusion pressure, tissue perfusion is decreased, the soft tissue becomes ischemic, and cells die. The most important clinical diagnostic signs of compartment syndrome are pain with passive stretching of the compartment and pain out of proportion to the results of the physical examination.
INTRODUCTION: The radiocarpal complex is the structure formed by the distal radioulnar, radiocarpal and midcarpal joints; these joints are compartments, each anatomically separated from the other. An appropriate arthrographic study with three-compartment injection better demonstrates the capsuloligamentous structures than conventional radiography. The diagnosis of any condition in this complex may therefore be easier to make. MATERIAL AND METHODS: From January 1993 to December 1996, twenty-six patients with mild to moderate wrist and carpal sprain and previously examined with radiography, were submitted to digital three-compartment arthrography at the Imaging Diagnostic Service of the Rizzoli Orthopedic Institute. Of 17 patients with previous radiographic diagnosis of scapholunar diastasis, 1 patient had a negative radiographic picture, 15 had an incomplete tear of the scapholunar ligament and 1 a double injury of the scapholunar and triquetro-lunar ligaments. Of 10 patients with mild to moderate triquetro-lunar diastasis, 8 had and arthrographic picture of pyramido-lunar ligament injury, 1 had a double injury of the triquetro-lunar and scapholunar ligaments and another one of triangular fibrocartilage complex injury. RESULTS: Three-compartment contrast agent injection permitted the diagnosis of interruptions between the different compartments and more injuries of scapholunar and triquetro-lunar ligaments than single compartment injection. We examined 27 patients with small arch injuries with three-compartment digital arthrography and found scapholunar diastasis in 17 (63%) and triquetro-lunar diastasis in 10 (37%). In the first group of 17 patients, three-compartment arthography demonstrated more scapholunar ligament injuries (13 cases) than single compartment injection; image subtraction, allowed by the digital technique, showed 2 injuries not visible otherwise. Injuries of the scapholunar and triquetro-lunar ligaments were demonstrated with and without digital subtraction. One patient had no ligament injury. In the other group of 10 patients, three-compartment arthrography showed more triquetro-lunar ligament injuries (6 cases) than single compartment injection; image subtraction demonstrated 2 injuries not visible otherwise in this group too. Injuries of the scapholunar and triquetro-lunar ligaments were demonstrated with and without digital subtraction. The injury of triangular fibrocartilage and contrast agent leak into soft tissues were shown in one patient with the injection of the distal radioulnar compartment alone, regardless of image subtraction. CONCLUSIONS: Arthrography, combined with conventional static and dynamic radiography, increases the detection rate of capsuloligament joint defects in the wrist-carpal complex. The three-compartment digital technique combines the advantages of fluoroscopic monitoring and videorecording and allows real time imaging of the contrast agent flow during injection in different compartments. Moreover, the digital technique permits the complete study of all joints in a single session, while image subtraction reveals even minimal ligament changes. This technique becomes therefore a fundamental tool for surgical planning.
INTRODUCTION: Tibial fractures are known to be associated with elevated compartment pressures, which may potentially result in a compartment syndrome. The Tibial Less Invasive Stabilization System (LISS PLT) is an internal fixator device that is designed for fixation of proximal tibia fractures. The technique includes submuscular placement of the implant along the lateral border of the tibia. Such placement of the Tibia LISS into the anterior leg compartment could increase compartment pressures, and therefore increase the risk of compartment syndrome. The objective of this prospective study is to determine whether submuscular placement of a tibia LISS fixator increases compartment pressures and what is the incidence of compartment syndrome. MATERIALS AND METHODS: Twenty-eight consecutive proximal tibia fractures were fixed using the Tibia LISS (LISS PLT). Compartment pressures in all four leg compartments were measured pre- and postoperatively. Diastolic pressures were recorded and perfusion pressures calculated. RESULTS: There were no statistically significant differences between pre- and postoperative compartment pressures. One patient out of twenty-eight developed an impending compartment syndrome after placement of the LISS implant. CONCLUSIONS: Submuscular fixation of the tibia with the Less Invasive Stabilization System does not cause a significant rise in leg compartment pressures, nor is it associated with an increased incidence of compartment syndrome.
The pharmacokinetic profiles of labelled Naja melanoleuca, Naja nivea, Naja nigricollis and Naja haje venoms and their alpha neurotoxins were determined following rapid i.v. injection into rabbits. The data obtained fitted a triexponential equation characteristic of a three-compartment open pharmacokinetic model comprising a central compartment 'blood', a rapidly equilibrating 'shallow' tissue compartment and a slowly equilibrating 'deep' tissue compartment. The distribution half-lives for the shallow compartment ranged from 3.2 to 5 min, reflecting the rapid uptake of venoms and toxins compared with 22-47 min for the deep tissue compartment denoting much slower uptake. The overall elimination half-lives, t1/2 beta, ranged from 15 to 29 hr, indicating a slow body elimination. Peak tissue concentration was reached within 15-20 min in the shallow tissue compartment. The corresponding values for the deep tissue compartment were 120 min for N. melanoleuca and N. nigricollis venoms and their toxins and 240 min for N. nivea and N. haje venoms and their toxins. Steady-state distribution between the shallow tissue compartment and the blood gave values of 0.50 and 0.92 (N. melanoleuca), 1.64 and 1.05 (N. nivea), 0.78 and 0.92 (N. nigricollis) and 1.70 and 1.03 (N. haje) for the venoms and their toxins, respectively. The corresponding values for the deep tissue compartment gave ratios of 3.31 and 3.44 (N. melanoleuca), 2.99 and 1.68 (N. nivea), 3.74 and 3.79 (N. nigricollis) and 1.39 and 2.46 (N. haje) for the venoms and their toxins, respectively. Ratios lower than unity indicate lower venom and toxin concentrations in the tissues than in the blood, while larger ratios denote higher tissue concentrations. The values thus reflect a higher affinity of the venoms and their toxins for the central than the shallow tissue compartment and for the deep tissue than the central compartment. The sites of action of the venoms seem to be located in the deep tissue compartment since most of the pharmacological, biochemical and electrocardiographic effects of the venoms started 30-60 min after i.v. injection. The mean residence time in the body, MRTb, ranged from 20.8 to 51.8 hr, which correlated well with the long duration of the pharmacological and biochemical effects induced by the venoms. The tissue distribution of the venoms and toxins was similar, with the highest uptake being in the kidneys, followed by the stomach, lungs, liver, spleen, intestine, heart and diaphragm. Very high radioactivity was found in the stomach contents, which reached values higher than the kidneys. Some of the biochemical markers were significantly changed by one or more venoms but the grouped parameters did not reflect significant changes in cardiac, renal, hepatic or electrolyte profiles as a function of time. It is concluded that antivenom, even if injected several hours after a cobra bite, is still capable of neutralizing the slowly eliminating venom. To speed up neutralization of the venom effects, doses of antivenom higher than the calculated in vitro neutralizing dose ought to be injected to compensate for the slow rate of transfer of antivenom to the tissues.
PURPOSE: In this article we question a basic concept in retinal pathology, which views the retina as composed primarily of neural elements, in a single compartment. METHODS: We suggest an alternative approach, centering on the epithelial-glial elements of the retina, dividing the retina into two distinct compartments. The framework of these two compartments is composed of two epithelial-like monostratified cell layers facing each other by their apical surfaces. This model is in agreement with the embryological development of the retina. RESULTS: Each compartment is composed of a monostratified cell layer in which neural elements are embedded and each is supplied by a different blood supply. The inner compartment, also referred to as the Muller cell compartment, extends between the inner and outer limiting membranes. The outer, or RPE, compartment extends between the outer limiting and Bruch's membranes. The border between the two compartments is formed by the outer limiting membrane (OLM). One simplified example utilizing the two-compartment concept is as follows: inner compartment edema (inner blood-retinal barrier breakdown) may manifest as cystoid edema, but not as serous retinal detachment, while outer compartment edema (outer blood-retinal barrier breakdown) may manifest as serous retinal detachment but not as cystoid edema, as long as the integrity of the OLM is maintained. CONCLUSION: A two-compartment approach to the structure of the retina, centering on non-neural elements, may enhance our understanding of some retinal pathologies. Various retinal diseases, mainly of vascular origin, are limited to one of the two compartments.
1. To examine whether cytosolic Ca2+ in smooth muscle cells distributes evenly, cytosolic Ca2+ levels were measured with two different Ca2+ indicators in the ferret isolated portal vein; a fluorescent indicator, fura-PE3, that shows the average Ca2+ level, and a photoprotein, aequorin, that preferentially shows a high Ca2+ compartment. 2. A noradrenaline (10 microM)-induced sustained contraction was associated with a sustained increase in the fura-PE3 signal, or a transient increase followed by small sustained increase in the aequorin signal. A high K(+)-induced contraction was associated with a sustained increase in both the fura-PE3 and aequorin signals. 3. A second application of noradrenaline or high K+ induced reproducible contractions and fura-PE3 signals. In contrast, the aequorin signal resulting from a second application of noradrenaline or high K+ was much smaller than the first signal. 4. Following a 13 h but not a 3 h resting period, the aequorin signal stimulated by noradrenaline or high K+ recovered, without any change in the contractile response. 5. In Ca(2+)-free solution, high K+ was ineffective, whereas noradrenaline induced only a small aequorin signal and contraction compared to those obtained in the presence of external Ca2+. After the addition of Ca2+, the first application of noradrenaline induced a large aequorin signal and a large contraction, although a second application induced a much smaller aequorin signal accompanied by a large contraction. 6. These results suggest that high K+ and noradrenaline increase Ca2+ in at least two cytosolic compartments; a compartment that is coupled to the contractile mechanism ('contractile' Ca2+ compartment; major portion of cytoplasm containing contractile elements) and a compartment that is not coupled to contractile mechanisms ('non-contractile' Ca2+ compartment; small sub-membrane area that does not contain contractile elements). On stimulation, the Ca2+ level in the 'contractile' compartment may increase to a level high enough to stimulate myosin light chain kinase but not so high as to consume aequorin rapidly. In contrast, the Ca2+ level in the 'non-contractile' compartment may increase so greatly that aequorin in this compartment is rapidly consumed. These two compartments may be separated by a diffusion barrier and, during a resting period, aequorin may slowly diffuse from the 'contractile' compartment to the 'non-contractile' compartment and thus restore the full aequorin signal. An increase in Ca2+ in the 'non-contractile' compartment seems to be dependent mainly on Ca2+ influx and partly on Ca2+ release.
The genome is organized into distinct chromatin compartments with at least two main classes, a transcriptionally active A and an inactive B compartment, broadly corresponding to euchromatin and heterochromatin. Chromatin regions within the same compartment preferentially interact with each other over regions in the opposite compartment. A/B compartments are traditionally identified from ensemble Hi-C contact frequency matrices using principal component analysis of their covariance matrices. However, defining compartments at the single-cell level from sparse single-cell Hi-C data is challenging, especially since homologous copies are often not resolved. To address this, we present MaxComp, an unsupervised method, for inferring single-cell A/B compartments based on 3D geometric considerations in single-cell chromosome structures-derived either from multiplexed FISH-omics imaging or 3D structure models derived from Hi-C data. By representing each 3D chromosome structure as an undirected graph with edge-weights encoding structural information, MaxComp reformulates compartment prediction as a variant of the Max-cut problem, solved using semidefinite graph programming (SPD) to optimally partition the graph into two structural compartments. Our results show that the population average of MaxComp single-cell compartment annotations closely matches those derived from ensemble Hi-C principal component analysis, demonstrating that compartmentalization can be recovered from geometric principles alone, using only the 3D coordinates and nuclear microenvironment of chromatin regions. Our approach reveals widespread cell-to-cell variability in compartment organization, with substantial heterogeneity across genomic loci. When applied to multiplexed FISH imaging data, MaxComp also uncovers relationships between compartment annotations and transcriptional activity at the single-cell level. In summary, MaxComp offers a new framework for understanding chromatin compartmentalization in single cells, connecting 3D genome architecture, and transcriptional activity with the cell-to-cell variations of chromatin compartments.
OBJECTIVE: Exercise-induced leg pain may be triggered by abnormally high compartment pressure. In addition to the more widely publicized anterior compartment syndrome, the deep posterior compartment syndrome can just as frequently occur, resulting in severe pain and disability due to muscle and nerve ischemia. BACKGROUND: Obtaining a thorough history and compartmental pressure measurements are the usual components in the accurate diagnosis of compartment syndromes. While few other disorders mimic compartment syndromes, differential diagnoses must be considered. Surgical management of deep compartment syndrome, consisting of fasciotomy or fasciectomy, or both, is successful for most patients. DIFFERENTIAL DIAGNOSIS: Tibial stress fracture or microfracture, tibial periostitis, tibial periostalgia, distal deep posterior chronic compartment syndrome, proximal deep chronic compartment syndrome, superficial lateral compartment syndrome, deep venous thrombosis, popliteal artery entrapment, or chronic compartment syndrome. UNIQUENESS: Chronic deep compartment syndrome is one of the most common causes of exercise-induced leg pain in aerobic athletes. Therefore, the athletic trainer must be able to recognize the condition. Signs, symptoms, diagnosis, and surgical management of chronic deep compartment syndrome, chronic periostalgia, and superficial lateral compartment syndrame in a 21-year-old Division IA track and field athlete are presented. CONCLUSIONS: With the correct diagnosis, persistent and methodical reevaluation, and appropriate management, the athlete can expect a successful treatment outcome.