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Biomedical subjects

M Carretta

Publications and source records attributed to M Carretta.

At least 19 recordsLinked to original sources
PubMed1999

[Balloon tamponade in penetrating liver lesions. Technical note].

BACKGROUND: The objective of this work was to evaluate the utility and the effectiveness of the intraparenchymatous balloon tamponade for transfixing lesions of the liver. An analysis is made of the results of an experimental surgical technique during 12 months in patients with gunshot wounds producing hepatic transfixing lesions. METHODS: Twelve patients have been treated, all of masculine sex, with middle age of 22 years, in which the hepatic transfixing lesions have been treated with intraparenchymatous balloon tamponade built intraoperatively with Nelaton and a drain of great latex. This system is filled with physiological solution and hydrosoluble contrast medium for further radiological controls. All the patients have been enrolled at the department of General Surgery of the Hospital "José Maria Vargas" of Caracas (Central University of Venezuela). RESULTS: This method has been used with good results, without postoperative bleeding and neither after the balloon removal. CONCLUSIONS: The intraparenchymatous balloon tamponade in the hepatic transfixing lesions is a sure procedure, rapid and easy, particularly in the emergency rooms of countries that have a high index of abdominal trauma with gunshot wounds and they are not always endowed with all the surgical medical requirements to treat these severe and difficult hepatic lesions.

Adolescent↗
PubMed1998

Collaterals of recurrent laryngeal nerve fibres innervate the thymus: a fluorescent tracer and HRP investigation of efferent vagal neurons in the rat brainstem.

The origin and course of efferent vagal fibers, which innervate the rat thymus, were investigated by a fluorescent retrograde double labeling method, using Fast blue (FB) and Diamidino yellow dihydrochloride (DY) as tracers. In the same animal, one tracer was injected into the cranial portion of the right lobe of the thymus and the other dye was deposited around the cut end of the right recurrent laryngeal nerve. The neuronal population giving origin to the recurrent nerve was mapped by using retrograde labeling with HRP applied to the central stump of the nerve. The HRP retrograde axonal transport showed that most efferent vagal fibers of the recurrent nerve have their perikarya in the nucleus retroambigualis (NRA), nucleus ambiguus (NA), and to a lesser extent in the nucleus retrofacialis (NRF). In fluorescent retrograde double labeling of thymus and recurrent laryngeal nerve both single and double labeled cells were found. The cells labeled by the injections into the thymus were colocalized with the neurons labeled by the tracer deposited in the recurrent laryngeal nerve to the NRA, NA, and NRF. Moreover along the rostrocaudal extent of the NRF and NA double labeled cells were present, showing that some of the thymic efferents are collaterals of the recurrent nerve fibers. Our experiments shown that some thymic vagal fibres originate from neurons of nucleus dorsalis nervi vagi (NDV) as demonstrated both by HRP and FB injected thymuses. The possible role of these efferents in thymic function is briefly discussed.

Amidines↗
PubMed1993

Treatment of severe diabetes mellitus for more than one year using a vascularized hybrid artificial pancreas.

We report the successful application of a hybrid artificial pancreas device for the treatment of severe diabetes mellitus induced by total pancreatectomy in two dogs. Control of the blood sugar was achieved for more than 1 year in these two animals without any immunosuppressive therapy. Although exogenous insulin was required therapy. Although exogenous insulin was required during the latter part of the study period, removal of the devices resulted in a rapid increase in the fasting blood sugar levels and the exogenous insulin requirements (P < 0.001 versus weeks 1-52 in both dogs). Metabolic studies, postexplant in vitro studies, and histologic analyses confirmed islet cell survival and insulin production by the devices. This hybrid artificial pancreas has a clear clinical potential for islet cell transplantation without immunosuppression.

Animals↗
PubMed1993

Use of magnetic resonance angiography in the pretransplant evaluation of portal vein pathology.

The assessment of portal vein patency in patients selected as candidates for orthotopic liver transplantation should be accomplished noninvasively and with great accuracy. Magnetic resonance angiography (MRA) is a new technique that is completely noninvasive and is capable of graphically assessing portal vein anatomy and blood flow. In an attempt to establish the accuracy of portal venous MRA, 74 patients with established cirrhosis underwent abdominal MRA prior to liver transplantation. MRA findings were correlated with surgical findings at the time of transplantation in all patients, and were shown to be extremely accurate. The three-dimensional images generated by MRA and computer postprocessing allowed for correct identification of portal venous anatomy in all of the patients examined. We conclude that MRA is an extremely useful method of determining portal venous anatomy in potential liver transplant patients, and potentially offers greater definition and clarify compared with other non-invasive methods.

Humans↗
PubMed1992

Adjustable nylon ties for abdominal wall closure.

A study in 64 patients with a high risk of wound dehiscence or eviscerated wounds or in whom repeat laparotomies for peritoneal lavages due to sepsis were planned was accomplished using adjustable nylon ties for the closure of the abdominal wall, either as retention sutures or as one-layer sutures. The adjustable nylon ties are described, as well as the technique for placing and adjusting them. It is concluded that the adjustable nylon ties can substitute advantageously for the conventional retention sutures since the former are wider, easy to place, and can be readjusted to the point that they can be opened completely if it is necessary and then closed again. This is especially useful when repeat laparotomies for peritoneal lavages are required in patients with intra-abdominal sepsis.

Abdominal Muscles↗
PubMed1992

Treatment of severely diabetic pancreatectomized dogs using a diffusion-based hybrid pancreas.

Long-term survival of dog islet allografts implanted in diabetic pancreatectomized dogs was achieved by islet encapsulation inside cylindrical chambers fabricated from permselective acrylic membranes (nominal M(r) exclusion of 50,000-80,000). Dog islets were isolated from the pancreases of outbred mongrel dogs by collagenase digestion. Chambers containing mean +/- SE 316 +/- 63K islet equivalents (mean islet volume, 558 +/- 111 mm3, purity 90-95%) were peritoneally implanted into six totally pancreatectomized dogs. The dogs were monitored for glycemic control by fasting and postprandial blood glucose determinations, and responses to both intravenous glucose (intravenous glucose tolerance test 0.5 g/kg) and oral glucose (oral glucose tolerance test 1 g/kg). All of the dogs required appreciably lower dosages of exogenous insulin therapy for control of fasting blood glucose levels, with the mean daily insulin dose dropping from 38 +/- 7 to 5 +/- 1 U/day during the 1st wk. Three recipients required no insulin for greater than 82, greater than 68, and 51 days. Intravenous glucose tolerance test K values (decline in glucose levels, %/min) at 1 and 2 mo postimplantation were 2.7 +/- 0.4 and 2.0 +/- 0.5, respectively compared with 3.5 +/- 0.5 before pancreatectomy. The glucose values during oral glucose tolerance tests at 2 wk, although returning to less than 125 mg/dl (less than 7.0 mM) by 2 h, exceeded the normal range, with peak values of 174 to 202 mg/dl (9.7 to 11.3 mM). These preliminary results are encouraging, and represent an important step in determining the feasibility of using this type of diffusion-based hybrid artificial pancreas as treatment for diabetes mellitus in humans.

Animals↗
PubMed1991

Transplantation of islet allografts and xenografts in totally pancreatectomized diabetic dogs using the hybrid artificial pancreas.

Previously the authors reported on a Hybrid Artificial Pancreas device that maintained patent vascular anastomoses in normal dogs and, when seeded with allogeneic canine islets, maintained normal fasting blood sugars (FBS) in diabetic pancreatectomized dogs. Eventual failure of these devices was believed to be related to loss of islet viability and/or insufficient islet mass. The current study evaluates the effect of increased islet mass produced by implantation of two islet-seeded devices in pancreatectomized dogs and compares the results with those from dogs that received a single device. Twelve of fifteen dogs receiving single devices showed initial function as determined by elimination or reduction of exogenous insulin requirement; four showed initial function and seven showed extended function (100 to 284 days). Excessive weight loss (more than 20%), despite normal FBS and insulin dependence, required that four animals in this latter group be killed. Devices seeded with xenogeneic islets have met with limited success. One dog that received two bovine islet-seeded devices achieved function for more than 100 days; the remaining bovine-seeded devices (n = 8) functioned for only 3 to 16 days. Porcine islet-seeded devices were assessed by intravenous glucose tolerance tests (IVGTT). Recipients of two devices seeded with allogeneic islets demonstrated improved IVGTT results when compared to those from pancreatectomized dogs and recipients of single devices but were abnormal when compared to intact animals. Histologic examination of device and autopsy material from all failed experiments was performed and showed no mononuclear cell infiltration of the islet chamber or vascular graft material, only a few incidence of device thrombosis, and varying degrees of islet viability as judged by morphologic and immunohistochemical evaluation. The authors believe they have demonstrated progress toward the development and clinical applicability of the Hybrid Artificial Pancreas.

Animals↗
PubMed1990

Rhinophyma-like cryptococcal infection as an early manifestation of AIDS in a hemophilia B patient.

A hemophilia B patient, seropositive for HIV antibodies since 1984, came to us in March 1989 with a severe necrotizing lesion of the nose. It was an erythematous lesion and looked like rhinophyma. Microbiological examination of the skin biopsy showed the presence of Cryptococcus neoformans. At the time of the study, the patient was in partial remission after 2 weeks of therapy with fluconazole per os 400 mg/day. He will be treated with the same therapy at maintenance dose (200 mg/day) for a long period.

Acquired Immunodeficiency Syndrome↗
PubMed1988

The Retzius cells in the leech: a review of their properties and synaptic connections.

1. The Retzius cells (RCs) project an axonal branch in each anterior, posterior and dorsal segmental root. 2. RCs are the only serotonin-containing neurons projecting to the periphery. 3. RCs are activated by mechano-sensory neurons, by serotonin-containing neurons and by two pairs of subesophageal neurons, Tr 1 and Tr 2. 4. RCs also receive an excitatory and an inhibitory input from sensilla. 5. These inputs could form two systems, one converging onto RCs of each ganglion and one distributing to other ganglia after processing by RCs. 6. RCs play a role in muscle tension, in mucous release and in swimming activity.

Animals↗
PubMed1987

Axonal projections of the Retzius cells to the dorsal segmental root in the leech Hirudo medicinalis.

The presence of RC's axon running in the dorsal root of the leech Hirudo medicinalis was studied by means of electrophysiological and neuroanatomical techniques. Electrical stimulation of the dorsal root gave invariably the antidromic invasion of the Retzius cell. This effect disappears after crushing the dorsal root between the stimulating electrode and the ganglion, and hence is not due to stimulus spread to the nearby posterior root. Anatomical evidence for an axon collateral running in the dorsal root was provided by catecholamine histofluorescence of the axonal branches of the RCs and by Lucifer Yellow intracellular injection into the RCs.

Animals↗
PubMed1987

Afferent sensillar inputs to the Retzius cell of the leech Hirudo medicinalis.

Water-wave and photic stimulation of the sensilla elicits synaptic potentials identical to those elicited by electrical stimulation of the segmental roots. Mechanical stimulation elicits a localized IPSP and a generalized EPSP in the RCs and an IPSP in the AE motoneurons. Photic stimulation gives rise to a generalized EPSP in the RCs alone. The impulse discharges elicited in the afferent fibers by the two kinds of stimuli is transmitted along the cord both anteriorly and posteriorly to the stimulated segment. This implies that the afferent impulses excite a pool of intersegmental neurons in each ganglion, which distribute their discharges to the adjacent ganglia. The evidence for occlusion between cordal and photically elicited volleys indicates that it shares with the sensillar input a common pool of interneurons. The possible functional significance of the inhibitory and excitatory inputs is discussed.

Afferent Pathways↗
PubMed1985

Role of the interval between axotomy and nerve suture on the success of muscle reinnervation: an experimental study in the rabbit.

The influence of the time interval between nerve transection and neurorrhaphy on motor and sensory reinnervation was studied experimentally in the rabbit. We evaluated the maximal tetanic tension, the amplitude of the compound action potential, and the retrograde transport of horseradish peroxidase 30 and 60 days after neurorrhaphy carried out at 0, 10, or 20 days after transection of the nerves to the medial and lateral gastrocnemius and soleus muscles. The results showed that the suture 20 days after transection was followed by a more precocious motor reinnervation, whereas the outgrowth of motor axons past the suture was not affected by the time interval between transection and neurorrhaphy. On the contrary, the best regrowth of afferent axons was obtained after an interval of 10 days between transection and suture. We conclude that the time interval did not influence motor axon growth, but was involved in the operation of mechanism(s) involved in the reestablishment of impulse conduction and/or synaptic efficacy. In contrast, the time interval appeared to be related to factors involved directly in the axonal elongation of afferent fibers.

Action Potentials↗
PubMed1985

Synaptic effects elicited in the Retzius cells of the leech Hirudo medicinalis by stimulation of the segmental roots.

Electrical stimulation of the segmental roots of each ganglion of Hirudo medicinalis, elicits in both Retzius' cells inhibitory and excitatory effects. The IPSP and EPSP are chemical in nature, being dependent on the membrane potential, and suppressed by high Mg++. Selective inactivation of one RC shows that the responses of the contralateral RC are not due to electrotonic coupling between the two cells, but to synaptic actions impinging upon the membrane of both RCs. The two synaptic potentials appear to be mediated by two set of fibres with a different threshold to electrical stimulation. Their actions on the RCs appear to be polysynaptic on the basis of central latency. Simultaneous stimulation of two roots shows evidence for occlusion for IPSP and summation for EPSP, confirming the polysynaptic nature of the effects. The possible functional significance of the inhibitory and excitatory pathways, is discussed.

Animals↗
PubMed1985

Lesions of the spine in heroin addicts.

The authors present 6 cases of spinal lesions in heroin addicts--3 infective, 3 traumatic. The striking feature about all these cases is the comparative absence of spinal symptoms. This underlines the importance of accurate and early diagnosis in these subjects.

Adolescent↗