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Biomedical subjects

M Stern

Publications and source records attributed to M Stern.

At least 145 records · Page 8Linked to original sources
PubMed1996

In vitro hydrolysis of gliadin and casein peptides: secondary defect in coeliac disease shown by organ culture.

BACKGROUND: Small-intestinal organ culture was used as an in vitro model of coeliac disease, studying biopsy specimens from patients with coeliac disease, cow's milk allergy, and controls. METHODS: Organ culture incubations were done using the pure gliadin peptide B3144 (amino acid sequences 3-56 of alpha-type gliadins) and a control peptide from casein (amino acid sequences 152-193 of alpha s1-casein). The importance of using negative controls was stressed by non-specific tissue damage. By reversed-phase high-performance liquid chromatography of organ culture supernatants, 27 specimens were further investigated. RESULTS: There was good retrieval of peptide calibration peaks after culture. Qualitative and quantitative evaluation of chromatography runs showed degradation of at least 29% of B3144 and 37% of Cas-P. Normal mucosa (controls and coeliac patients on a gluten-free diet) was able to hydrolyse peptide fractions completely, whereas incubation with damaged mucosa (coeliac disease, cow's milk allergy) left initial peptides. CONCLUSION: It is concluded, using a pure single gliadin peptide, that deficient peptide hydrolysis in coeliac disease was a secondary event.

Adolescent↗
PubMed1996

[Bronchial anastomotic complications after pulmonary transplantation. X-ray computed tomographic evaluation].

PURPOSE: To determine the sensitivity and specificity of CT in depicting bronchial anastomotic complications after lung transplantation. MATERIALS AND METHODS: A retrospective, blinded review of 105 CT scans obtained after single (n = 17) or double (n = 10) lung transplantation in 27 patients was done by two radiologists in consensus. CT images, were analyzed with respect to the status of bronchial anastomoses, with three possible answers given to the readers: normal, dehiscence, or stenosis. CT features were correlated to bronchoscopic and follow-up findings, which were considered as standard of reference. RESULTS: CT had a 60% sensitivity and 98% specificity for the diagnosis of bronchial dehiscence, and 40% and 99% for the diagnosis of anastomotic stenosis. One case of bronchial disruption was diagnosed on CT scan only and subsequently confirmed by repeated bronchoscopy. CONCLUSION: In our study, CT has a low sensitivity but a high specificity in the detection of bronchial anastomotic complications after lung transplantation. However, CT remains useful in some cases, as it can show complications not seen bronchoscopically.

Adult↗
PubMed1996

Human monocyte-derived macrophage phagocytosis of senescent eosinophils undergoing apoptosis. Mediation by alpha v beta 3/CD36/thrombospondin recognition mechanism and lack of phlogistic response.

Eosinophils may mediate tissue injury in a number of allergic diseases. Previously, we reported that eosinophils constitutively undergo apoptosis (programmed cell death) in culture. As this led to phagocytosis of the intact senescent cell by macrophages, we proposed that apoptosis represented an injury-limiting eosinophil disposal mechanism. Ingestion of apoptotic neutrophils by human monocyte-derived macrophages (M phi s) was found to be mediated by adhesive interactions between thrombospondin and the M phi alpha v beta 3 vitronectin receptor integrin and M phi CD36. As this failed to elicit a pro-inflammatory response from M phi s, we sought evidence that this specific, nonphlogistic clearance mechanism may operate in eosinophil disposal. In this study, we found that M phi ingestion of apoptotic eosinophils was specifically inhibited by monoclonal antibodies to M phi alpha v beta 3, CD36, and thrombospondin and by other inhibitors of this recognition mechanism including RGD peptide and amino sugars. Furthermore, not only did M phi ingestion of intact apoptotic eosinophils fail to stimulate release of the phlogistic eicosanoid thromboxane, but there was also a lack of increased release of the pro-inflammatory cytokine granulocyte/macrophage colony-stimulating factor. However, increased release of these mediators was observed when M phi s took up senescent post-apoptotic eosinophils that had been cultured long enough to lose plasma membrane integrity. The data indicate that the nonphlogistic alpha v beta 3/CD36/thrombospondin macrophage recognition mechanism is available for clearance of intact senescent eosinophils undergoing apoptosis. Furthermore, our findings suggest that, by contrast, phagocytosis of post-apoptotic eosinophils may elicit undesirable pro-inflammatory responses.

Amino Sugars↗
PubMed1996

Diagnosis and management of root fractures and periodontal ligament injury.

Although root fractures are among the less common oral injuries (6 percent), a careful diagnostic evaluation of such injuries is required to arrive at an appropriate treatment plan. The position of the fracture in the root will determine the proper management. The problem of luxation due to trauma often involves the use of dental splints, which, if not properly designed, may cause root resorption, loss of alveolar bone, pulpal necrosis and pulp canal obliteration. The guidelines for the type of splint to use and conditions under which it should be placed are presented.

Dental Pulp↗
PubMed1996

Improving the professional self-efficacy cognitions of immigrant doctors with Balint groups.

Immigrant doctors have been found to exhibit professional distress, especially if they are retrained to another medical specialty. This study looks at the effects of a long-term Balint group in increasing professional self-efficacy cognitions of immigrant physicians treating drug addicts in a home-based community program in their adopted homeland. Results of the group showed positive significant changes in specific self-efficacy cognitions related to treatment of drug addicts in the community, and an increase in psychosocial self-efficacy from baseline to three other assessment points. The importance of long-term Balint groups with doctors in general and with retraining immigrant doctors in particular is also carefully elucidated.

Community Mental Health Services↗
PubMed1995

Changes of brain anatomy in patients with posttraumatic stress disorder: a pilot magnetic resonance imaging study.

No abnormalities in magnetic resonance images were recorded in patients with posttraumatic stress disorder other than an increased incidence (50%) of a small cleft in the callosal-septal interface, a cavum of the septum pellucidum. A similar grade of cavum was obtained in 14% of normal volunteers matched for age, socioeconomic background, and military experience. The cavum is believed to have antedated the disorder and is conceived to be a neurodevelopmental aberration. The possibility that the cavum is a marker of vulnerability to stress in psychopathology is discussed.

Adult↗
PubMed1995

A controlled investigation of current and premorbid personality: characteristics of Parkinson's disease patients.

It has been suggested that before development of motor symptoms, Parkinson's disease (PD) patients with idiopathic display a specific cluster of personality traits consisting of increased rigidity, conscientiousness, industriousness, orderliness, and cautiousness. The idea of such a distinctive premorbid personality profile remains controversial. This hypothesis was reexamined using a methodology that expands on previous studies. Patients with idiopathic PD, probable Alzheimer's Disease (AD), and medical controls with nonneurological chronic progressive motor disorders were rated by a close relative on the NEO-Personality Inventory (PI) to compare current and premorbid personality profiles. For PD and control subjects, current and past self-ratings were also obtained. Results do not support the postulated distinctive PD personality either premorbidly or following onset of symptoms. Both in terms of the premorbid personality profile and perceived changes in personality post-dating the onset of illness, PD patients are similar to AD patients. Though not differing from medical controls premorbidly, after developing symptoms, PD patients were described as less extroverted; less exploratory and curious; and less organized, goal directed, and disciplined.

Age Factors↗
PubMed1995

Crypt-villus differentiation reflected by lectin and protein binding to rat small intestinal brush border membranes.

To compare differentiation along the crypt-villus axis in adult rats with changes observed in postnatal maturation with respect to binding capacities for lectins and food proteins, crypts and villi were isolated by in vivo perfusion and in vitro incubation. Brush border membranes were prepared from adults and newborns, and binding of 125I-labeled lectins and food proteins was assessed by airfuge ultracentrifugation. Crypt and villus membrane protein patterns looked almost identical, unlike newborn membranes. Considerable shifts in lectin binding to membranes were observed during postnatal maturation, but not in crypt-villus differentiation. For instance, fucose-specific lectin binding patterns in both preparations resembled the general adult mode. Contrary to differences in food protein binding between newborn and adult membranes, food protein binding did not show a consistent significant difference between membranes of crypt and villus origin in adult animals. In conclusion, membrane differentiation along the crypt-villus axis was found to follow a pattern dissimilar from neonatal maturation as far as protein and carbohydrate composition and food protein binding were concerned.

Aging↗
PubMed1995

Epidemiology of obesity and its link to heart disease.

Univariate analyses of many prospective studies have demonstrated that obesity increases the likelihood of developing cardiovascular disease. However, multivariate analyses have yielded more inconsistent results. Some studies have indicated that lean individuals have a greater total mortality than normal-weight individuals, but this may be attributable to the higher proportion of smokers in the lean population. Mexican Americans, a population with a high incidence of obesity, have the same mortality rate as non-Hispanic white Americans, suggesting that obesity does not increase their death rate. In the United States, the percentage of the population that is overweight has increased sharply since the 1970s, but the mortality rate has actually decreased. The increase in body weight has had little effect on mortality, possibly because factors associated with obesity, like hypertension, are treated more effectively. Large-scale clinical trials are required to determine the true effects of obesity on cardiovascular disease, diabetes and total mortality rate.

Black or African American↗
PubMed1995

Comparative study of brain magnetic resonance imaging findings in patients with low-tension glaucoma and control subjects.

PURPOSE: To evaluate the presence of central nervous system degeneration in patients with low-tension glaucoma using magnetic resonance imaging. METHOD: Ten patients with low-tension glaucoma and ten age-matched control subjects underwent magnetic resonance imaging. Cortical atrophy and cerebral infarcts were graded from "0" (normal) to "3," which was done subjectively by two neuroradiologists independently in a masked fashion. Midsagittal corpus callosum section was evaluated by measuring the thickness and cross-sectional area. RESULTS: There was a significantly greater extent of cerebral infarcts in the patients with low-tension glaucoma (P = 0.02). The thickness of the body (P = 0.03) and genu (P = 0.04) of the corpus callosum were thinner in the patients with low-tension glaucoma. The corpus callosum cross-sectional area was smaller in the low-tension glaucoma group (P = 0.04). There were no significant differences in the other parameters in this study. CONCLUSION: This study suggests a greater extent of cerebral infarcts and corpus callosum atrophy in patients with low-tension glaucoma. This may imply a greater degree of neuronal degeneration, possibly on an ischemic basis in low-tension glaucoma.

Aged↗
PubMed1995

The introduction of two silent mutations into a CFTR cDNA construct allows improved detection of exogenous mRNA in gene transfer experiments.

Phase one clinical trials for gene therapy of cystic fibrosis are in progress using either liposomes or adenoviral vectors for CFTR gene transfer to epithelial cells in the airways. In addition to electrophysiological measurements, expression of vector CFTR is usually assessed by RT-PCR. We have developed a CFTR-expression vector, pCFAS, that simplifies the distinction of transgene-derived CFTR mRNA from endogenous mRNA. Two point mutations were introduced into CFTR cDNA which eliminated a SphI restriction site and created a new, unique AgeI restriction site. Neither mutation altered the predicted amino acid sequence of the protein. Restriction digestion of RT-PCR products from cells transfected with pCFAS allowed the differentiation of transgene and endogenous CFTR transcripts. To verify function of the mutated CFTR, the plasmid was transferred into freshly obtained nasal epithelial cells from CF patients ex vivo using cationic liposomes. Fluorescence microscopy using the halide-sensitive fluorophore SPQ demonstrated restoration of cAMP-mediated Cl- secretion. This plasmid will be useful for CFTR gene transfer studies in vitro and in vivo.

Base Sequence↗
PubMed1995

Comparison of three methods for culturing throat swabs from cystic fibrosis patients.

In patients with cystic fibrosis who do not produce sputum, deep throat swabs are cultured for potential respiratory pathogens. Usually these swabs are directly streaked onto selective agar media. In a study of 50 pediatric cystic fibrosis patients, we compared this traditional method using rayon swabs with two methods having quantitative modifications: calcium alginate swabs eluted in Ringer's lactate and rayon swabs eluted in normal saline. The eluates were then processed quantitatively (three-step dilution series). The yield of potential pathogens was significantly higher with the two quantitative methods. Overall, the combination of alginate with Ringer's lactate was superior to the combination of rayon with saline, although only some of these differences achieved statistical significance.

Adolescent↗
PubMed1995

Identified octopaminergic neurons provide an arousal mechanism in the locust brain.

1. Habituation is the declining responsiveness of a neural circuit (or behavior) to repetitive stimulation. Dishabituation (or arousal) can be brought about by the sudden presentation of an additional, novel stimulus. A clear example of arousal in the locust is provided by the visual system: the habituated response of the descending contralateral movement detector (DCMD) interneuron to repetitive visual stimuli can be dishabituated by a variety of other visual and tactile stimuli. 2. Application of octopamine to the locust brain and optic lobes dishabituates the DCMD in a manner similar to the effect of visual and tactile stimulation. 3. The locust CNS contains two pairs of octopamine-immunoreactive cells, the protocerebral medulla 4 (PM4) neurons, that could potentially mediate this dishabituation effect; PM4 neurons arborize in the optic lobe, they contain octopamine, and they respond to the same visual and tactile stimuli that dishabituate the DCMD. 4. To investigate whether PM4 activity dishabituates the DCMD, we recorded intracellularly from one of the PM4 neurons while recording extracellularly from the DCMD. When the PM4 neuron is injected with hyperpolarizing current to render it completely inactive, the DCMD exhibits its characteristic habituation to a moving visual stimulus. However, depolarizing the PM4 neuron, to produce action potentials at approximately 20 Hz, significantly increases the number of DCMD action potentials per stimulus. 5. The PM4 neurons may therefore play an important role in dishabituating the DCMD to novel stimuli. This effect is presumably mediated by PM4 neurons releasing endogenous octopamine within the optic lobe.

Animals↗
PubMed1995

Increased neuronal excitability conferred by a mutation in the Drosophila bemused gene.

We have identified a new gene in Drosophila on the basis of a mutation that affects both behavior and neuronal excitability. This mutation, called bemused (bem) is the result of a P element insertion at cytological position 85D. Flies defective at bem display greatly reduced coordination, flight ability and fertility. The bem mutation also affects synaptic transmission at the larval neuromuscular junction. In particular, bem larvae display a more rapid onset of augmentation than bem+ larvae. This effect is potentiated by the potassium channel blocking drug quinidine. The increased transmitter release that occurs in bem mutants following repetitive nerve stimulation is accompanied by the appearance of extra action potentials in the motor neuron. We conclude that the bem mutation increases neuronal excitability, possibly as a result of a defect in an ion channel structural or regulatory gene.

Animals↗
PubMed1995

A study of Israeli blood donors, asymptomatic carriers of hepatitis C virus, in relation to liver disease, cryoglobulinemia and transmission.

In order to study the asymptomatic hepatitis C virus (HCV)-positive blood donors in Israel we analyzed their sera for HCV-RNA using the polymerase chain reaction technique. We found that 0.44% of blood donors were anti-HCV positive. Of those who had repeatedly positive anti-HCV, 82% had evidence of HCV-RNA. One-third of them had elevated liver enzymes, but no detectable cryoglobulins were found in their sera. Although HCV-RNA was detected in the majority of the patients, we were unable to demonstrate vertical or horizontal transmission among the family members of our carrier population.

Adult↗