Biomedical subjects

G Mall

Publications and source records attributed to G Mall.

At least 37 records · Page 2Linked to original sources

PubMed2000

Determination of sex from femora.

The determination of sex from bones or bone fragments considerably contributes to identifying unknown bodies or skeletal remains. Due to temporal change and regional differences anthropometric standards have to be constantly renewed. The present study provides measurements of femoral dimensions in a contemporary German population and analyses sexual dimorphism by discriminant analysis. Maximum length (male: 46.4+/-2.4 cm, female: 43.4+/-2.4 cm), maximum midshaft diameter (male: 3.1+/-0.2 cm, female: 2.8+/-0.2 cm), condylar width (male: 8.4+/-1.0 cm, female: 7.7+/-0.5 cm), vertical head diameter (male: 4.9+/-0.3 cm, female: 4.4+/-0.3 cm), head circumference (male: 15.7+/-0.8 cm, female: 13.8+/-1.0 cm) and transverse head diameter (male: 4.9+/-0.3 cm, female: 4.3+/-0.3 cm) were measured in 170 femora, 100 from male (age: 16-92 years, mean: 60.8 years; body height: 153-190 cm, mean: 171 cm) and 70 from female (age: 20-96 years, mean: 72 years; body height: 146-175 cm, mean: 161 cm) individuals. In the discriminant analysis (leave-one-out-method) 67.7% of cases could be grouped correctly with the maximum length alone, 72.4% with the maximum midshaft diameter, 81.4% with the condylar width, 86.8% with the vertical head diameter, 87.7% with the head circumference and 89.6% with the transverse head diameter. The stepwise procedure with all head measurements showed that the results for the transverse head diameter could not be improved. With all measurements subjected to stepwise procedure 91.7% of cases could be classified correctly combining midshaft diameter and head circumference (D=3.012xmidshaft diameter in cm+0.780xhead circumference in cm 20.569).

Adolescent↗

PubMed2000

Experimental and clinical assessment of the accuracy of knee extension measurement techniques.

The purpose of this study was to analyze the accuracy of commonly used techniques for the measurement of knee extension and to compare them with a new measurement device. The bars of an external fixator were used to determine reference knee extension angles of 15 human cadavers. These angles were compared with measurements of knee extension on radiographs limited to the knee joint. Extension was determined in various knee positions using a generic goniometer and a novel long arm goniometer. In a clinical study, two independent examiners categorized knee extension performance according to the IKDC. Sixteen knees with deficits in the range of motion were rated using a generic goniometer, a long arm goniometer and the novel extension measurement device. The radiological measurement of knee extension angles that were restricted to the shaft of femur and tibia had a systematic error of -5.2 +/- 1.9 degrees compared with the lines created by the centers of rotation. In the experimental setup, the mean absolute deviations were 3.92 +/- 1.41 degrees with a generic goniometer and 1.22 +/- 0.20 degrees with the extension measurement device. The variance of the measurements was significantly lower (2.64 +/- 0.28) than with the generic goniometer (23.72 +/- 4.39; P < 0.05). Correspondence in the IKDC rating was 63% using a standard goniometer, 50% with the long arm goniometer, and 96% using the novel device. Radiological measurements of knee extension limited to the area of the knee joint deviates systematically from measurements of the total axis of the bones. A precision goniometer that utilizes bony landmarks of the tibia and femur is superior in accuracy compared with standard and long arm goniometer techniques.

Adult↗

PubMed2000

Effects of ACE inhibition and bradykinin antagonism on cardiovascular changes in uremic rats.

BACKGROUND: Cardiovascular death continues to be a major problem in renal failure. Structural abnormalities of the heart and the vasculature contribute to the increased cardiovascular risk. They are ameliorated by angiotensin-converting enzyme (ACE) inhibitors, but because of the nonspecifity of ACE inhibition, it is uncertain whether the beneficial effect is mediated by interfering with angiotensin II (Ang II) or by modulating other effector systems, for example, bradykinin. METHODS: To assess a potential role of bradykinin, subtotally nephrectomized Sprague-Dawley rats (SNX) received either the ACE inhibitor Ramipril (Rami, 0.2 mg/kg body weight p.o.), the specific B2 bradykinin receptor antagonist Hoe140 (0.2 mg/kg body weight, s.c.), or a combination of both, and were compared to sham-operated controls. To separately assess the effect of Ramipril on development and reversal of structural abnormalities, animals were either treated from the third day after SNX or from the fourth week after SNX onward (0.01 mg/kg body weight, p.o.). RESULTS: Heart and aorta were evaluated by morphometric and stereologic techniques. The weight of the perfused left ventricle, as an index of cardiac hypertrophy, was significantly higher in untreated SNX. While it was significantly lower in animals with early and late Ramipril treatment, the beneficial effect was completely antagonized by Hoe140. The wall-to-lumen ratio of intramyocardial arterioles was significantly higher in untreated SNX compared with controls, but failed to be modified by administration of either Ramipril or Hoe140. In the heart, the intercapillary distance was significantly higher in SNX, but it was not lowered by either early or late Ramipril or Hoe140 treatment. Treatment of SNX with Hoe140 alone, however, resulted in a marked further increase in intercapillary distance. The wall thickness of the aorta was significantly higher in SNX than in controls; early and late Ramipril treatment prevented such increase, and this effect was antagonized by Hoe140. CONCLUSION: These findings illustrate that bradykinin plays an important role for the beneficial effect of Ramipril in preventing (and potentially reversing) abnormal cardiovascular structure in uremic hypertensive rats.

Adrenergic beta-Antagonists↗

PubMed2000

Morphology of coronary atherosclerotic lesions in patients with end-stage renal failure.

BACKGROUND: An excessive rate of cardiac death is a well-known feature of renal failure. Coronary heart disease is frequent and the possibility has been raised that the natural history of the coronary plaque is different in uraemic patients. We assessed the morphology of coronary arteries in patients with end-stage renal failure and compared them with coronary arteries of matched non-uraemic control patients. METHODS: Fifty-four cases were identified at autopsy who met the inclusion criteria: cases, end-stage renal disease (n=27); controls, non-renal patients with coronary artery disease (n=27). At autopsy all three coronary arteries were prepared at corresponding sites for investigations: (i) qualitative analysis (after Stary), (ii) quantitative measurements of intima and media thickness (by planimetry), (iii) immunohistochemical analysis of the coronary plaques and (iv) X-ray diffraction of selected calcified plaques. RESULTS: Qualitative analysis of the coronary arteries showed significantly more calcified plaques of coronary arteries in patients with end-stage renal failure. Plaques of non-uraemic patients were mostly fibroatheromatous. Media thickness of coronary arteries was significantly higher in uraemic patients (187+/-53 microm vs 135+/-29 microm in controls) and intima thickness tended to be higher (158+/-38 microm vs 142+/-31 microm) but this difference was not statistically significant. Plaque area (4.09+/-1. 50 mm(2) vs 4.39+/-0.88 mm(2)) was comparable in both groups. Lumen area, however, was significantly lower in end-stage renal patients. Immunohistochemical analysis of the cellular infiltrate in coronary arteries showed no major differences in these advanced plaques of uraemic and non-uraemic subjects. CONCLUSION: Coronary plaques in patients with end-stage renal failure are characterized by increased media thickness and marked calcification. In contrast to the previous opinion the most marked difference compared to non-uraemic controls does not concern the size, but the composition of the plaque. Deposition of calcium within the plaques may contribute to the high complication rate in uraemic patients.

Aged↗

PubMed2000

Capillary/myocyte mismatch in the heart in renal failure--a role for erythropoietin?

BACKGROUND: Chronic renal failure is characterized by remodeling of the heart with left ventricular hypertrophy (increasing oxygen demand) and capillary deficit leading to capillary/myocyte mismatch (decreasing oxygen supply). Erythropoietin (Epo) has known angiogenic properties causing endothelial cell activation, migration and sprouting, mediated at least in part via the JAK/STAT (Janus kinase/signal transducers and activators of transcription) pathway. In uraemic cardiac hypertrophy the presence of diminished capillary supply implies that capillary growth does not keep pace with development of hypertrophy. To investigate whether this was due to a deficit of the angiogenic hormone Epo we examined whether Epo levels are altered and whether an increase in haematocrit by administration of rhEpo influences capillary supply, i.e. capillary/myocyte mismatch in experimental renal failure. METHOD: Male Spraque-Dawley rats were either subjected to partial renal ablation or sham operation. Only modest amounts of renal tissue were removed so that the rats were not anemic. Subgroups of rats received either human (rh)Epo alone or in combination with unspecific antihypertensive treatment (dihydralazine plus furosemide) in order to control the Epo induced rise in blood pressure. Capillary supply was measured stereologically as capillary length per volume myocardium using the orientator method. RESULTS: Capillary length density was reduced by approximately 25% after partial renal ablation (3237+/-601 vs 4293+/-501 mm/mm(3) in controls). It was not statistically different in animals with partial renal ablation+rhEpo+antihypertensive treatment (3620+/-828 mm/mm(3)) compared to partial ablation alone. CONCLUSION: The study shows that lack of Epo does not cause, or contribute to, the deficit of capillary growth in the hypertrophied left ventricle of rats with renal failure. In addition, a rise in haematocrit is not accompanied by beneficial effects on alterations of cardiovascular structure in experimental renal failure.

Animals↗

PubMed1999

Unexpected death in persons with symptomatic epilepsy due to glial brain tumors: a report of two cases and review of the literature.

Two cases of unexpected death in persons with epileptic seizures due to a brain tumor are presented which encompassed an astrocytoma WHO grade II and an anaplastic astrocytoma WHO grade III. A 35-year-old man was found somnolent and disoriented at home. A computed tomography (CT) scan revealed a tumor of the right frontal lobe suggestive for an oligodendroglioma. During an angiographic examination the patient experienced an epileptic seizure. Some weeks later, the man was found dead in front of his house with a fresh bite mark of the tongue. Neuropathological examination revealed an astrocytoma WHO grade II of the right frontal lobe. A 47-year-old man plunged into a swimming-pool and was found submerged some minutes later. After resuscitation he survived comatose for 8 days but finally died due to severe hypoxic brain damage. He had been operated on a brain tumor of the temporal lobe 1 year before the accident. Neuropathological examination revealed residual tumor tissue at the operation site corresponding to an anaplastic astrocytoma WHO grade III. Although rare, death in persons with epileptic seizures due to brain tumors is an important mechanism of death encountered by the forensic pathologist.

Adult↗

PubMed1999

Determination of calcaneal ultrasound properties ex situ: reproducibility, effects of storage, formalin fixation, maceration, and changes in anatomic measurement site.

The objective of this study was to determine the reproducibility of ultrasonic bone properties with a system for measuring calcanei ex situ; the influence of changes of the measurement site; and the effects of fixation, storage, and maceration. We examined 14 fixed calcanei and 12 fresh bones. Ultrasonic measurements were performed ex situ after degassing, using an Achilles+ system and a special positioning device. The instrument precision was 0.16% for speed of sound (SOS), 1.4% for broadband ultrasonic attenuation (BUA), and 1. 8% for the stiffness index (SI). The short-term precision was 0.54%, 1.9%, and 2.8%, respectively. A defined shift of the measurement site (5 mm distal of the middle) led to unpredictable changes in ultrasound (US) properties (r = 0.65 for SOS, 0.82 for BUA, and 0.75 for SI). Embalment with 4% formalin/96% alcohol caused a systematic decrease in SOS, an increase in BUA, and a decrease in SI (mean = -12.7 units; P < 0.001), the effect increasing with time. However, values at 6 months of fixation and later were highly correlated with those in fresh specimens (r = 0.95 for the SI). Two weeks storage in degassed and normal solution had only modest effects on ultrasound properties. Maceration did not lead to a systematic increase or decrease of ultrasound variables, but introduced unpredictable changes (r = 0.64-0.94). We conclude that in comparative biomechanical studies it is feasible to measure calcaneal specimens embalmed in formalin/alcohol ex situ, if the primary interest is not in the absolute values but in the correlation with mechanical failure loads at other skeletal sites.

Aged↗

PubMed1999

Energy loss due to radiation in postmortem cooling. Part B: Energy balance with respect to radiation.

With the help of the law of Stefan and Boltzmann and a model for the cooling of exposed skin derived from the data of Lyle and Cleveland, the radiation energy loss ER can be calculated according to the following formula: [formula in text] where epsilon represents the emissivity of the skin (0.98), sigma the Stefan-Boltzmann constant, AR the radiating surface area, TS(0) the skin temperature at death, TE the environmental temperature and Z' = 0.1017 the gradient of the skin temperature curve. Additionally, an energy loss due to conduction and convection EC has to be taken into account. Comparing the energy losses due to radiation, conduction and convection with the decrease ET of the thermal energy in the body, calculated from mean heat capacity (3.45 kJ/(kg degrees K)), body mass and decrease of mean body temperature, there is a surplus of energy in the very early postmortem period, which can be explained only by an internal source of energy EI. Alltogether the following balance equation can be formulated: ET + EI = ER + EC Since the body temperature decreases in the early postmortem period, EI can be estimated by: EI(t) > or = max (ER(t) - ET(t), 0). The values obtained range up to 500 kJ for a medium sized (175 cm), medium weight (75 kg) body at an environmental temperature of 5 degrees C and are compatible with estimations of Lundquist for supravital energy production by breakdown of glycogen.

Body Mass Index↗

PubMed1999

Biomechanical analysis of stress distribution in the human temporomandibular-joint.

The positions of the head of the mandible, of the articular disc and the outline of the temporal surface are digitized from sagittal MRI-scans of the temporomandibular joint of a 32-year-old subject in 5 different positions of occlusion. The stress distribution in the joint is calculated on the basis of these data. For each position of the condyle, the momentary center of rotation in the head of the mandible and the tangent attached to the temporal surface are determined. The line connecting these two points indicates the direction of the resulting compressive force. Furthermore, the extension of the area available to the force transmission is estimated. By means of these parameters the stress distribution is calculated independently from the position. The analyses show that the temporomandibular joint is slightly eccentrically loaded in all positions. The increase of the stresses is in all cases oriented caudo-ventrally. The results are verified in an anatomical specimen of the articular tuberculum. The trabecular structures as well as the subchondral bone-lamella of the articular tuberculum are functionally adapted to the analyzed stress situations.

Adult↗

PubMed1999

The significance of the anatomy of the skull base for mechanical modelling: a comparative study.

The present paper aims at analysing the significance of the anatomical structures of the human skull base for mechanical modelling. Three different Finite-Element (FE)-models of the human neurocranium were developed. The most complex model (1242 solid cuboid elements) contains holes and spaces functionally simulating the foramina and fissures and additional element layers for the inner relief of the skull base (petrous temporal and sella). Of the less complex models, one (1256 solid cuboid elements) includes only the 3 cranial fossae, while the other (400 solid cuboid elements) represents a rotationally symmetrical ellipsoid with a hole for the foramen magnum. Two linear static loadcases, one with a transverse loading direction (pressure of 250 kg on the left temporal surface, bearing on the right temporal surface) and the other with a sagittal loading direction (pressure of 250 kg on the frontal surface, bearing on the occipital surface) were computed. The loadcase analyses show, qualitatively and quantitatively, similar equivalent von Mises stress values and distributions in the two more complex models while the elementary geometric model leads to significantly different absolute stress values and distributions. The results of the most complex model are highly compatible with experimental observations on transverse and sagittal fractures of the skull base.

Biomechanical Phenomena↗

PubMed1999

The cyclic pattern of the immunocytochemical expression of oestrogen and progesterone receptors in human myometrial and endometrial layers: characterization of the endometrial-subendometrial unit.

Immunocytochemistry of oestrogen receptor (ER) and progesterone receptor (PR) expression of the whole uterine muscular wall and the endometrium was performed in order to obtain morphological and functional insights into the regulation of cyclic uterine peristalsis, which is confined to the endometrium and the subendometrial myometrium and serves functions such as rapid and sustained sperm transport. The study revealed that the subendometrial myometrium or stratum subvasculare with a predominantly circular arrangement of muscular fibres exhibits a cyclic pattern of ER and PR expression that parallels that of the endometrium, whereas the outer portion of the uterine wall composed of the stratum vasculare and supravasculare, which represents the bulk of the uterine musculature, does not exhibit a cyclic pattern of ER and PR expression. According to ontogenetic and phylogenetic data from the literature, the outer myometrium is of non-paramesonephric origin with functions confined to parturition, while the inner myometrial layer together with the glandular epithelium and the stroma of the endometrium is of paramesonephric origin with various functions during the cycle in addition to those during pregnancy and parturition. The inner quarter of the stratum vasculare adjacent to the stratum subvasculare constitutes a transitional zone in that the cyclicity of receptor staining becomes, in radial direction, gradually less expressed. Morphologically this zone corresponds to the inner part of the stratum vasculare where its muscular fibres blend with those of the stratum subvasculare.

Adult↗

PubMed1999

Treatment of cardiovascular changes in renal failure--ACE inhibition, endothelin receptor blockade or a combination of both strategies?

ACE-I and specific ETA receptor blockade comparably prevented the development of structural cardiovascular alterations such as LVH, myocardial interstitial expansion and wall thickening of intramyocardial and extracardiac arteries in experimental renal failure. However, the decrease in myocardial capillary supply and the concomitant increase in intercapillary distance could only be prevented by ETA receptor antagonism. These capillary changes which have been shown to occur in experimental renal failure as well as in uraemic patients play an important role in the pathogenesis of reduced cardiac ischaemia tolerance in renal failure. The data argue for a potential role of the local renin-angiotensin system as well as of the ET system in the pathogenesis of cardiovascular changes in renal failure and for ET receptor blockade as a new therapeutic option in the treatment of these alterations. In particular, myocardial capillary supply, which is particularly important for ischaemia tolerance in renal failure, seems to be modulated and regulated predominantly by ET-1. In contrast to what was found with respect to structural and functional changes of the kidney in various experimental models of renal damage, a combination therapy--at least in the doses used--does not seem to provide additional benefit in the prevention of cardiovascular changes compared with the respective monotherapies.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1999

Hypertrophy of intramyocardial arteriolar smooth muscle cells in experimental renal failure.

Wall thickening of intramyocardial arteries in patients with chronic renal failure may contribute to the increased susceptibility of the uremic heart to ischemic injury. In this context, the following questions arise: (1) Is intramyocardial wall thickening in experimental renal failure due to hypertrophy, hyperplasia or both? (2) Which stimuli trigger wall thickening? Using novel stereologic techniques (Nucleator, Selector), intramyocardial arteries were examined in sham-operated and subtotally nephrectomized (SNX) Sprague Dawley rats with moderate renal failure of 8 wk duration. Systolic BP during the experiment was not significantly different in both groups. Absolute and relative left ventricular weight, wall thickness (5.69 +/- 1.11 microm versus 4.42 +/- 0.99 microm), and wall-to-lumen ratio of intramyocardial arteries (0.117 +/- 0.03 microm/microm versus 0.089 +/- 0.01 microm/microm) were significantly greater in SNX than in sham-operated rats. The mean cell and nuclear volume of intramyocardial arteriolar smooth muscle cells was significantly increased in SNX rats (650 +/- 230 microm3 versus 430 +/- 90 microm3 and 26 +/- 4.5 versus 19.9 +/- 2.2 microm3, respectively). In parallel, the total arteriolar wall volume was significantly greater in the left ventricle of SNX (+58%) compared with sham rats. In contrast, the total length of all left ventricular arteries was comparable in both groups. The increase in mean cell volume without significant change in cell number indicates that arteriolar wall thickening in the heart of SNX rats is explained by hypertrophy rather than hyperplasia of arterial smooth muscle cells. This finding in a nonhypertensive experimental model of chronic renal failure contrasts with findings in spontaneously hypertensive rats. Independent of BP and left ventricular hypertrophy, specific growth signals must act on cardiac arteriolar smooth muscle cells.

Animals↗

PubMed1998

Energy loss due to radiation in postmortem cooling. Part A: quantitative estimation of radiation using the Stefan-Boltzmann law.

Conduction and convection are assumed to account for most of the energy loss from the dead body to the (cooler) environment. There are no quantitative estimations in the literature for the contribution of radiation to heat loss. The aim of the present paper was to estimate the radiation energy loss in postmortem cooling. The Stefan-Boltzmann law is used and combined with a single-exponential model for the cooling process of the skin derived from experimental data of Lyle and Cleveland (1956). The influence of various factors (e.g. skin temperature, environmental temperature, body mass and body height) on the amount of radiation emitted was investigated. The radiation energy is quantitatively described as a function of time. The radiation energy loss ranged from approximately 200 kJ in small (165 cm) and lean (50 kg) bodies at room temperature (20 degrees C) to approximately 600 kJ in tall (185 cm) and over-weight (100 kg) bodies at outdoor temperature (5 degrees C) in the first hour postmortem.

Body Constitution↗

PubMed1998

Cardiac remodelling in experimental renal failure--an immunohistochemical study.

BACKGROUND: In view of the high rate of cardiac death in renal failure, the factors involved in the genesis of structural changes in the heart are of obvious interest. The present study addresses the issue whether growth factors known to be involved in cardiac remodelling are abnormally expressed in rats with renal failure. METHODS: Sprague Dawley rats were subjected to binephrectomy (2 days) or subtotal nephrectomy (8 weeks). Controls were sham-operated rats and rats with Goldblatt hypertension. Cardiac expression of proliferating cellular nuclear antigen (PCNA), of growth factors and of their receptors (PDGF, TGF-beta, VEGF) was investigated immunohistochemically. In addition, cardiac PDGF-and TGF-beta mRNA were assessed using quantitative RT-PCR. RESULTS: Eight weeks after subtotal nephrectomy (SNX) significantly increased expression of PCNA and PDGF was found in the cardiac interstitium and of PCNA and VEGF in the walls of intramyocardial arteries. In addition, PCNA-positive cardiomyocytes were noted in SNX. Similar changes were not seen in the hearts of hypertensive controls, i.e. rats with renovascular hypertension, despite slightly higher blood pressure and more pronounced left ventricular hypertrophy (LVH). While significant changes of cardiac PDGF- and TGF-beta mRNA expression could not be documented in the whole-heart homogenates 8 weeks after subtotal nephrectomy, 2 days after bilateral nephrectomy PDGF mRNA was significantly increased and TGF-beta mRNA decreased. CONCLUSION: The observations demonstrate (i) specific activation of cardiac interstitial cells after SNX, (ii) activation of postmitotic cardiomyocytes, possibly predisposing to apoptosis, (iii) increased expression of PDGF in the cardiac interstitium and in the wall of intramyocardial arteries, (iv) increased expression of VEGF associated with hypertrophy of arterial smooth muscle cells. These results were not explained by elevated blood pressure or LVH, respectively.

Acute Kidney Injury↗

PubMed1998

Cardiac involvement in proximal myotonic myopathy.

Proximal myotonic myopathy (PROMM) is a recently described autosomal dominantly inherited disorder resulting in proximal muscles weakness, myotonia, and cataracts. A few patients with cardiac involvement (sinus bradycardia, supraventricular bigeminy, conduction abnormalities) have been reported. The cases of three relatives with PROMM (weakness of neck flexors and proximal extremity muscles, calf hypertrophy, myotonia, cataracts) are reported: a 54 year old man, his 73 year old mother, and 66 year old aunt. All three presented with conduction abnormalities and one had repeated, life threatening, sustained monomorphic ventricular tachycardia. This illustrates that severe cardiac involvement may occur in PROMM.

Aged↗

PubMed1998

Coxsackievirus genome in myocardium of patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy.

Enteroviruses are known as major infectious agents for inflammatory heart diseases such as myocarditis and dilated cardiomyopathy (DCM). Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC) is characterized by replacement of right ventricular myocardium by fatty and fibrous tissue. In about 65% of patients inflammatory infiltrates suggest an inflammatory or infectious etiopathogenesis. To test this hypothesis, we investigated endomyocardial biopsies of patients with ARVC, with myocarditis or DCM, and from patients with non-inflammatory cardiac disorders for the presence of enteroviral genome. Enteroviral RNA with homology to coxsackieviruses type B was detected in 3 of 8 patients with ARVC (37.5%), in 7 of 23 patients with myocarditis or DCM (30.4%), but in none of 5 patient with non-infectious myocardial diseases (p < 0.05 compared to ARVC patients). These results support earlier suggestions that coxsackievirus infection of the myocardium is possibly related to the pathogenesis of ARVC.

Adult↗

PubMed1998

Myocyte/capillary mismatch in the heart of uremic patients.

Experiments indicate that capillary density is reduced in the hypertrophied left ventricle of rats with subtotal nephrectomy compared to control rats with similar BP and left ventricular hypertrophy, suggesting that in uremia, hypertrophying cardiomyocytes outgrow their capillary supply. No information on myocardial capillary supply in humans is currently available. The hearts of nine dialyzed patients, nine patients with essential hypertension, and 10 normotensive control subjects at postmortem were obtained. Subjects with stenosing coronary lesions and left ventricular pump failure were excluded. Special sampling procedures were used to exclude stereologic artefacts. Capillaries were specifically stained with ulex lectin and analyzed by stereologic techniques. Length density of myocardial capillaries (Lv; mm/mm3) was significantly (P < 0.001) lower in dialyzed patients (1483 +/- 238) than in patients with essential hypertension (1872 +/- 243) or in normotensive control patients (2898 +/- 456). In parallel, myocyte diameter and volume density of myocardial interstitial tissue were significantly (P < 0.001) increased in uremic patients compared to patients with essential hypertension and control patients, respectively. Diminished left ventricular capillary supply in renal failure must increase critical oxygen diffusion distance in the myocardium, thus exposing cardiomyocytes to the risk of hypoxia. It is unknown whether such reduced ischemia tolerance can be reversed by increasing oxygen supply (e.g., by reversing anemia).

Aged↗