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Biomedical subjects

M Rubin

Publications and source records attributed to M Rubin.

At least 19 recordsLinked to original sources
PubMed1992

The effect of short-term lipid infusion on liver function and biliary secretion in rats.

This study was undertaken to determine the effect of various lipid emulsions on the hepato-biliary system in rats. Rats were randomly divided into six groups and infused continuously for 48 hr with either long-chain triglycerides (LCT), medium-chain triglycerides (MCT) or a mixture of MCT and LCT. One group infused with physiological saline solution served as controls. Throughout this period the rats received a fat free diet ad libitum. During the last hour of lipid infusion bile was collected for determination of bile flow and composition. Subsequently, the rats were sacrificed and the morphology and lipid content of the liver determined. Only LCT lipid emulsions induced morphological changes and increased liver cholesterol content. In two rats infused with radiolabeled LCT, no labeled cholesterol was found in the liver, indicating that the excess hepatic cholesterol level may originate from enhanced cholesterol mobilization to the liver. Biliary cholesterol and phospholipid concentrations in LCT-treated rats were also elevated, as was the lithogenic index, whereas the other emulsions had no such effects. None of the emulsions affected the plasma liver function tests or bile flow. We therefore conclude that the lithogenicity of the bile in rats is directly related to the lipid components of the total parenteral nutrition and the type of triglyceride infused.

Animals↗
PubMed1992

Effect of lipid infusion on bile composition and lithogenicity in patients without cholesterol gall stones.

A prospective study was performed to investigate the effect of short term lipid infusion on bile composition and its lithogenicity in humans. Thirty five patients shown to be free of cholesterol gall stones participated in the study. Starting 48 hours before surgery they were infused randomly with a lipid emulsion of either long chain triglycerides (LCT) or a mixture of medium and long chain triglycerides (MCT/LCT) (50%/50%) for six hours each 24 hours. A group of patients infused with a solution of 5% glucose in NaCl 0.9% served as a control. Bile samples were obtained by puncture of the gall bladder during operation. Both lipids caused an increase in biliary cholesterol and phospholipids but this effect was more pronounced and significant (p < 0.001) only with the MCT/LCT emulsion. The fatty acid composition of biliary phospholipids was not affected by either lipid infusion. The cholesterol saturation index increased significantly (p < 0.005) with the MCT/LCT emulsion and there was shortening in the nucleation time but this was not significant. There was no effect on the distribution of cholesterol between micelles and vesicles. This study shows that infusion of MCT/LCT lipid emulsion can cause lithogenic changes in bile composition in humans and may thus contribute to sludge formation and cholelithiasis during long term parenteral nutrition.

Bile↗
PubMed1992

Sensory nerve abnormalities in brachial plexopathy.

Sensory nerve action potential (SNAP) amplitude should be abnormal in brachial plexopathies (BP) which cause axonal degeneration in distal segments. Fifty-six patients with BP were identified. In diffuse BP, 22/25 (88%) showed low amplitude or absent median or ulnar SNAP. Three of 5 patients with upper trunk BP had low amplitude or absent SNAP (1 median, 1 radial, 1 lateral antebrachial cutaneous). Seventy-five percent of patients with lower trunk/medial cord BP had low amplitude or absent SNAP (8/24 median, 18/24 ulnar). Overall, 82.5% of patients had low amplitude or absent SNAP when a sensory nerve in the distribution of signs was studied. Testing multiple sensory nerves to include symptomatic regions enhances the diagnostic yield of SNAP in BP.

Action Potentials↗
PubMed1992

A prospective randomized trial comparing the infectious and noninfectious complications of an externalized catheter versus a subcutaneously implanted device in cancer patients.

PURPOSE: To compare the frequency of infectious episodes or other problems occurring with an externalized catheter (Hickman) versus a subcutaneously implanted device (Port-a-Cath, Pharmacia, Piscataway, NJ) in cancer patients, we performed a prospective, randomized study in 100 cancer patients (age range, 5 to 74 years). PATIENTS AND METHODS: Patients who were chemotherapy candidates and required an indwelling catheter were monitored prospectively and evaluated during the 180 days after the insertion of the catheter and again at time of study closure. The frequency of catheter use, reason for access, and any problems that might have been related to catheter use were noted. All data were collected prospectively and included the patient's age, sex, underlying malignancy, temperature, and leukocyte and absolute granulocyte counts at the time of catheter insertion and when complications occurred. The time to and reason for removal of the catheter, as well as any intercurrent infectious or mechanical problems, were also determined. RESULTS: Most of the infections that occurred were caused by gram-positive organisms, especially staphylococci or streptococci. A total of 22 complications (11 in each group) resulted in removal of the central line. Only one infection in the Hickman catheter group and four in the Port-a-Cath group led to removal of the central line. All other infectious episodes were successfully treated without removal of the catheters. The mean device life was 230 days for the Hickman catheter and 318 days for the Port-a-Cath (not significant). CONCLUSION: There were no differences between the two study groups regarding incidence of documented infections or mechanical or thrombotic complications.

Adolescent↗
PubMed1992

Electrophysiologic changes in lumbar spinal cord after cervical cord injury.

Spontaneous activity on the EMG examination is traditionally ascribed to disease of the lower motor neuron when present in muscles well below the level of para- or quadriplegia despite the absence of any detectable peripheral nerve injury. It is uncertain whether it reflects transient paralysis of transmission (related to clinical spinal shock) or irreversible postsynaptic damage. We performed serial EMG studies of lower extremities and paraspinal muscles on eight young, previously healthy adults, commencing 2 to 9 weeks after acute cervical cord injury. All had stimulated single-fiber EMG (SFEMG) studies at 6-month intervals to determine whether irreversible postsynaptic damage of the anterior horn cell had occurred. MRI and nerve conduction excluded patients with evidence of distal cord injury or peripheral neuropathy. All patients had spontaneous activity in all muscles tested, persisting after spinal shock had resolved. Jitter was present on SFEMG in three of eight patients 6 months after injury. Four of five patients retested 12 months after injury had abnormal jitter, including three who initially had normal SFEMG studies. We conclude that there is electrophysiologic evidence of trans-synaptic distal cord dysfunction following acute spinal cord injury. SFEMG studies suggest that anterior horn cell dropout occurs during the 1st year after injury.

Adolescent↗
PubMed1992

[Implanted subcutaneous venous catheter for prolonged intravenous treatment].

Subcutaneous venous catheter devices were implanted in 104 patients between January 1989 and June 1991. In 90% the implantation was performed under local anesthesia as an ambulatory procedure. In 85% the catheter was implanted for long-term chemotherapy and in 15% for intravenous feeding, antibiotic treatment or dialysis. There were postoperative complications in about 10%, the most frequent being infection of the surgical wound or of the catheter canal. Venous thrombosis, cutaneous necrosis and catheter occlusion were observed in only 5%. The main advantages of the method are its convenience for the patient, ease of installation and low rate of complications. From our experience we conclude that the implanted subcutaneous venous catheter is a simple and effective procedure for prolonged intravenous treatment.

Ambulatory Surgical Procedures↗
PubMed1992

The epidemiology of cervical cancer and its precursors.

Cervical cancer is considered to be a preventable disease because of its lengthy preinvasive state, the effectiveness of screening programs, and the availability of effective treatment options for preinvasive lesions. Thus, identifying women with a greater probability of developing the disease is important to promoting early detection and instituting prompt treatment. Questions concerning risk factors that influence a woman's chances of developing cervical cancer are being addressed through research. Nurses who understand the epidemiology of cervical cancer and who are skilled in taking comprehensive health histories can play a major role in early detection and prompt treatment of cervical cancer by educating all women, including sexually active teenagers, about obtaining regular gynecologic screening exams.

Clinical Protocols↗
PubMed1991

Physico-chemical characterization of Intralipid emulsions.

Fat emulsions containing soy triacylglycerols (100-300 g/l) and egg-yolk phospholipids (12 g/l) are often used for intravenous feeding. Previous studies have shown that these emulsions contain chylomicron-like emulsion particles of diameters of 300-400 nm and excess phospholipids aggregated as vesicles (liposomes), which remain in the infranatant upon floatation of the emulsion particles by ultracentrifugation. This work is devoted to the characterization of the commercial lipid emulsions commonly denoted Intralipids, with special emphasis on the presently ill-defined liposomes. The lipid particles composing commercial lipid emulsions (10%, 20% and 30% Intralipids, Kabivitrum Nutrition) were characterized by the combined use of physical and chemical methods. Each of the emulsions was fractionated by ultracentrifugation in saline into a 'cream' layer which floats to the top of the dispersion upon ultracentrifugation and a relatively transparent infranatant. The cream layer contains large emulsion particles of diameters ranging from 300 to 400 nm, in agreement with theoretical considerations based on their chemical composition as determined by chemical analysis. The infranatants contain about 1 g/l triacylglycerols in addition to phospholipids (from 7.2 g/l in 10% Intralipid to 2.4 g/l in 30% Intralipid) in the form of smaller particles of 70-100 nm diameter. Cryo-transmission electron microscopy shows that the infranatants contain vesicles (mostly unilamellar) at the side of residual small emulsion particles. This conclusion is also consistent with the distribution of phospholipids between outer and inner lamellae, as determined by 31P-NMR.

Fat Emulsions, Intravenous↗
PubMed1991

Stimulatory effect of counterflow centrifugal elutriation in large-scale separation of peripheral blood monocytes can be reversed by storing the cells at 37 degrees C.

Transfusion of peripheral blood monocytes may be of benefit as adjuvant treatment of leukopenic patients with serious infections. To study the feasibility of this approach, a large-scale monocyte separation procedure employing leukapheresis, density gradient centrifugation, and counterflow centrifugal elutriation was established. By processing 5 to 6 liters of normal donor blood, it was possible to obtain a mean of 1.1 x 10(9) (range: 0.5-1.7 x 10(9) cells) of mononuclear cells, of which 89% (range: 82-94%) were monocytes by Wright's stain morphology. When the elutriation was performed in XVIVO-10, a commercially available, serum-free medium developed for adoptive immunotherapy, spontaneous secretion of superoxide by the monocytes was significantly higher than for monocytes elutriated in Hanks' balanced salt solution without calcium and magnesium or non-elutriated peripheral blood mononuclear cells. This stimulated state of the monocytes was observed both immediately after elutriation and after overnight storage at 4 degrees C, and it was not affected by the type of storage vessel used. Overnight storage of the monocytes at 37 degrees C resulted in a reversal of the stimulated state of the cells. Monocytes elutriated in XVIVO-10 and kept overnight at 4 degrees C released high amounts of arachidonic acid. A subsequent decrease in this release was seen after additional storage at 37 degrees C for 18 hours. These observations demonstrate that separation and storage variables have important effects on the state of stimulation of monocytes. Further investigations of such variables may suggest improved procedures for preparation and storage of these cells, as well as possible ways to stimulate monocytes prior to transfusion.

Arachidonic Acid↗
PubMed1991

Distant effects of locally injected botulinum toxin: a double-blind study of single fiber EMG changes.

We used single fiber electromyography (SFEMG) to study 42 patients who had enrolled in a double-blind, placebo-controlled trial undertaken to assess the efficacy of botulinum toxin (BTX) injection of neck muscles to treat torticollis. SFEMG in a limb muscle was performed before treatment, 2, and 12 weeks after injection of placebo or BTX. Before treatment, the mean jitter was 26.8 microsec in patients who were to receive BTX, and 25.7 microsec in the placebo group. Two weeks after injection, mean jitter in the group receiving BTX was 43.6 microsec. In the placebo group, it was 26.5 microsec (P = less than .05). Twelve weeks after injection, mean jitter in the BTX group was 35.5; for the placebo group it was 24.5. Fiber density did not change in any patient during the study. There were no remote clinical effects of BTX. Injection of BTX into muscles affected with focal dystonia is a promising and safe treatment, but there are subclinical effects on uninjected muscles.

Adult↗
PubMed1991

Large amplitude sensory action potentials in myelopathy: an observation.

Subjects with at least one sensory action potential (SAP) amplitude greater than 2 SD above the age-matched mean during standard nerve conduction tests were evaluated for evidence of spinal cord disease. From a total of 153 subjects, 16 had at least one large amplitude SAP and 12 of 16 (75%) had a documented myelopathy. While a mechanism has yet to be determined, this observation suggests that SAP amplitudes greater than 2 SD above normal may be correlated with clinical evidence of injury to the central nervous system.

Action Potentials↗
PubMed1991

Helper T-cell responses in children infected with human immunodeficiency virus type 1.

Helper T-cell function was evaluated in 34 children infected with human immunodeficiency virus type 1, by assessing interleukin-2 production after stimulation of peripheral blood mononuclear cells with recall antigens (influenza virus, tetanus toxoid), allogeneic HLA, and phytohemagglutinin. In addition, helper T-cell function was correlated retrospectively with the incidence of opportunistic and bacterial infections. Four patterns of helper T-cell function were observed: (1) 7 (21%) of the 34 children responded to all stimuli, (2) 7 (21%) of them responded to alloantigens and phytohemagglutinin but not to recall antigens, (3) 7 (21%) responded to phytohemagglutinin but not to recall antigens or alloantigens, and (4) 13 (37%) did not respond to any of these stimuli. There were no significant differences related to different routes of acquisition among patients. Patients with functional helper T-cell defects had a history of more opportunistic (p = 0.03) and bacterial (p less than 0.001) infections than did patients with intact helper T-cell function. Thus distinct patterns of helper T-cell dysfunction exist in children infected with human immunodeficiency virus type 1 and correlate with higher frequency of infections. Comparisons of in vitro helper T-cell responses to these stimuli may be useful for detecting early functional helper T-cell defects and for monitoring progression of disease.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Entrapment of an accessory superficial peroneal sensory nerve.

A 29 year old man had an accessory branch of the superficial peroneal nerve which entered the foot by rostro-caudally traversing the lateral malleolus laterally. The nerve was entrapped by a fascial band, resulting in pain over the lateral malleolus and dorsum of foot. Symptoms resolved when the nerve was surgically released.

Adult↗
PubMed1991

Granulocyte colony-stimulating factor enhances the phagocytic and bactericidal activity of normal and defective human neutrophils.

Granulocyte colony-stimulating factor (G-CSF) stimulates proliferation of myeloid cells and may be a valuable adjunct in prevention and treatment of neutropenia-associated infections. Neutrophil (PMNL) phagocytic and microbicidal functions against Staphylococcus aureus and Candida albicans blastoconidia were therefore evaluated. Bacterial phagocytosis and bactericidal activity were significantly enhanced by approximately 50%-70% after preincubation of normal PMNL with G-CSF in concentrations of 1000-4000 units/ml for 10 min at 37 degrees C. G-CSF in similar concentrations enhanced the defective bactericidal activity of PMNL from HIV-1-infected patients by approximately 70%-150% and reached the baseline control PMNL killing. However, G-CSF enhanced neither phagocytosis nor fungicidal activity of normal PMNL against C. albicans blastoconidia. These data demonstrate that G-CSF enhances the antibacterial but not the antifungal activities of human PMNL in vitro and also improves the defective PMNL bactericidal activity of HIV-1-infected patients.

AIDS-Related Complex↗
PubMed1991

Serum immunoglobulin G subclasses in children infected with human immunodeficiency virus type 1.

We studied serum concentrations of IgG subclasses in 47 human immunodeficiency virus 1-infected (17 asymptomatic and 30 symptomatic) children. Thirty-nine of 47 (83%) had an abnormality of at least 1 subclass. Sixteen had only elevated IgG1, 6 had only elevated IgG3 and 12 had elevated IgG1 and IgG3 concentrations. IgG2, IgG4 and combined IgG2-IgG4 deficiency was found in 3, 4 and 4 patients, respectively. IgG2 concentrations did not differ between patients with (n = 23) or without (n = 24) bacterial infections. Additionally the number of bacterial infections was similar between the patients with normal or low IgG2 and/or low IgG4. These data indicate that IgG subclass abnormalities are found in most children with human immunodeficiency virus 1 infection, but quantitative deficiencies of specific subclasses do not appear to explain the high frequency of bacterial infections occurring in these patients.

Acquired Immunodeficiency Syndrome↗