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Biomedical subjects

M Halpern

Publications and source records attributed to M Halpern.

At least 73 records · Page 4Linked to original sources
PubMed1996

Acid rain in Laos and Thailand.

Acid rain has an impact on forestry and human health. Forest degradation was noticed in the early 90's in Laos, a country without polluting industries nor intense automobile traffic. Therefore, in 1993-1994, we collected rain in one location in Thailand (Bangkok) and 4 in Laos (Luang Prabang, Vientiane, Savannaketh, Pakse); measured pH in each sample and resistivity in 2 locations. We obtained sequential meteorological satellite pictures showing the far motion of clouds, their location and course, and ultimately rain over Indochina. We conclude that acid rain forms over Thailand and falls in Laos (Vientiane, Pakse). We also measured peak flows in large groups of children, adults both non-smokers and chronic heavy smokers, in all five locations. Except for a small number of individual variations, we could not correlate the presence of acid rain and deterioration of pulmonary function in these subjects. However, we recommend active measures to curb pollution both in Thailand and Laos.

Acid Rain↗
PubMed1996

A computerized medical standards system to help place impaired employees.

The paper describes a knowledge-distribution system that supports decisions on placement of impaired employees. The knowledge base consists of job profiles and medical profiles. The job profiles list tasks and the physical abilities they require. Twenty-one abilities describe the task demands. Active workers rated the exertion, frequency and importance of the physical ability required for each task. Thirty-nine work conditions were rated this way. Using identical scales, experts assessed the impact of impairments on the physical abilities of individuals and the tolerance of work conditions. The screening matches the job profile against the impairment profile. This process has been automated. The program lists tasks and work conditions that may compromise an impaired employee. This information can be used to accommodate employees, restrict duties or design a rehabilitation program. Also, the paper discusses the impact of the system on the operations of medical services within an organization.

Disability Evaluation↗
PubMed1995

Differential localization of G proteins in the opossum vomeronasal system.

Gi2 alpha and G(o) alpha proteins were immunohistochemically localized, respectively, to the rostral and caudal accessory olfactory bulb of Brazilian opossums. In the vomeronasal organ, Gi2 alpha- and G(o) alpha-immunoreactive neurons were located in the middle and basal layers, respectively, of the sensory epithelium. Both G protein antibodies stained the microvillar surface of the epithelium and the nerve bundles in the subepithelial mucosa.

Animals↗
PubMed1995

Lectin histochemical identification of carbohydrate moieties in opossum chemosensory systems during development, with special emphasis on VVA-identified subdivisions in the accessory olfactory bulb.

Lectins, sugar-binding molecules of nonimmune origin, were used in this study to describe the development of the main olfactory and vomeronasal systems in the Brazilian gray short-tailed opossum, Monodelphis domestica. A battery of seven lectins of the N-acetylgalactosamine/galactose-binding group was used. Of the seven lectins, only two, Vicia villosa agglutinin (VVA) and Griffonia (Bandeiraea) simplicifolia lectin I-isolectin B4 (GS I-B4), were specific to the vomeronasal system. The other five lectins recognized carbohydrates in both chemosensory systems, although the binding was more intense in the accessory olfactory system. Furthermore, whereas six of the lectins stained the adult opossum accessory olfactory bulb (AOB) homogeneously, the VVA lectin distinguished two regions of the AOB. Similar to the expression of olfactory marker protein (OMP) (Shnayder et al. [1993] Neuroreport 5:193-196), the rostral half of the AOB stained much darker with VVA than the caudal half, and the onset of the restricted pattern of staining at age 45 days also coincided. We conclude that 1) GS I-B4 and VVA recognize cell surface carbohydrate moieties specific to the vomeronasal, but not to the main olfactory, system, and 2) the carbohydrate moiety that is recognized by the VVA lectin, presumably terminal N-acetyl-galactosamine, is both temporally and spatially restricted in the opossum AOB. These results are discussed in the framework of other known spatially restricted molecules of the two major nasal chemosensory systems.

Acetylgalactosamine↗
PubMed1995

Laparoscopic removal of an abdominal pregnancy adherent to the appendix after ovulation induction with human menopausal gonadotrophin.

The laparoscopic management of tubal pregnancies has become a standard form of treatment. We present, for the first time, a successful laparoscopic approach in the management of early abdominal pregnancy. Although it is difficult to reach conclusions from such limited published experience, it nevertheless appears that early abdominal pregnancies can be treated via operative laparoscopy. The possible advantages of such a therapeutic approach include lower morbidity and mortality, and a better fertility prognosis.

Adult↗
PubMed1995

Acid mucin and high molecular weight cytokeratin in prostatic lesions: evaluation of a combined histochemical and immunohistochemical stain.

OBJECTIVE: To evaluate the presence of acid mucins and high molecular weight cytokeratin (KER) in prostatic lesions using a combined histochemical and immunohistochemical stain consisting of Alcian blue at pH 2.5(AB) with a strept-avidin-biotin complex (SAB) staining for KER (SAB-KER). MATERIALS AND METHODS: Sections were obtained from archival paraffin blocks which included 20 cases of prostatic carcinoma, 30 cases of benign hyperplasia, and five cases of basal cell hyperplasia. Sections were stained for mucosubstances using the AB stain, for KER using SAB-KER and by both AB and SAB-KER, the combined stain (CS). RESULTS: With the CS stain KER, which is present in the prostatic basal cells, was not detected in malignant glands and in 60% of these cases intraluminal blue-stained acidic mucin was seen. On the other hand, all benign hyperplastic prostatic glands were devoid of intraluminal acidic mucin and showed staining for KER of their basal cells. Areas of basal cell hyperplasia were strongly positive for KER and intraluminal acidic mucin was seen in one case. Each of the stains separately gave similar results to the CS method but the contrast between the areas of carcinoma and hyperplasia was accentuated by the CS, and small foci of carcinoma were easily detected. CONCLUSION: The combined AB+SAB-KER stain is quicker to perform and allows the simultaneous appraisal of acid mucin and KER.

Avidin↗
PubMed1994

Tuberculosis in liver transplant patients.

Tuberculosis has been increasing especially in urban areas and in immunosuppressed patients; however, the incidence and factors associated with tuberculosis in OLT patients are unknown. Five of 550 patients who underwent OLT at the Mount Sinai Medical Center during a 5-year period were noted to have tuberculosis. The mean age of the patients was 49.2 years; there were 3 males and 2 females and 3 were foreign born. One of 5 had a prior history of tuberculosis. Tuberculin skin tests performed before transplant revealed 1 positive and 2 anergic reactions. The preoperative chest x-ray revealed apical fibrosis in 2 patients and bilateral apical disease with a nodule in 1 patient. Tuberculosis developed from 2 to 57 months after surgery in 4/5 patients. One had miliary lesions of the peritoneum discovered at the time of OLT. One patient had recent contact with a patient with pulmonary tuberculosis. At presentation, fever was present in 4 of 5 patients, pulmonary lesions in 3 patients, meningitis in 2; during hospitalization, 1 had a liver abscess and disseminated intravascular coagulation and peripheral gangrene. Lymphocytosis was noted in the pleural (1), peritoneal (1), and cerebrospinal fluid (1). Acid-fast smears were positive in bronchoalveolar lavage fluid (1), peritoneal isolates (1), and liver biopsy (1). All patients had positive cultures for Mycobacterium tuberculosis. These isolates were all sensitive to isoniazid, streptomycin, rifampin, ethambutol, and pyrazinamide. Four of 5 patients were treated with isoniazid and rifampin, 2 received pyrazinamide, 2, amikacin, 2, ofloxacin, and 2, ethambutol. Three of 5 patients are doing well on antituberculous therapy and 2 expired with tuberculosis as the cause of death. In OLT patients with unexplained fever, tuberculosis including extrapulmonary and disseminated disease should be considered since the mortality rate is very high. Liver transplantation can be performed in the presence of active peritoneal tuberculosis with the use of judicious antituberculous therapy. The role of preventive therapy is controversial, though use in certain high risk patients is suggested.

Adult↗
PubMed1994

Identification of chemoattractant receptors and G-proteins in the vomeronasal system of garter snakes.

Garter snakes respond to purified chemoattractants derived from prey. The specific binding sites for one of these chemoattractants, ES20, in the vomeronasal organ was saturable and reversible. Binding sites for ES20 were abolished by heating or greatly reduced by Pronase digestion. ES20 chemoattractant activity and receptor binding required Ca2+. Binding of ES20 to sensory epithelium derived from animals with bipolar neurons depleted by denervation was reduced 22-43% as compared to control animals. However, there was an upregulation of the ES20 receptor population in the nonsensory cells following nerve cuts. Three G-proteins (Gs, Gi, and G(o)) were tentatively identified using immunoreactivity and ADP-ribosylation techniques. Gi and G(o) proteins were shown to be coupled with ES20-receptor and effectors as evidenced by: 1) the affinity of ES20-receptor was decreased by GTP gamma S; 2) ES20-receptor binding caused a reduction in ADP-ribosylation of pertussis toxin-susceptible G-proteins, and the inhibitory effect of ES20-receptor on ADP-ribosylation was attenuated by GDP beta S; 3) the effect of ES20-receptor on ADP-ribosylation of the pertussis toxin-susceptible G-proteins could be mimicked by G-protein activators, such as GTP gamma S or AlF3; 4) ES20-receptor binding resulted in a decrease of the basal level of cAMP; 5) the binding of ES20 to its receptors caused an increase in the level of D-myo-inositol 1,4,5-trisphosphate.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Urinary tract infection in men with AIDS.

OBJECTIVE--To investigate whether bacteriuria and, specifically, symptomatic urinary tract infection (UTI) occur with increased frequency in men with HIV infection. METHODS--In this cross-sectional study we investigated three groups of men, aged from 18 to 50 years. Group A was composed of patients with a diagnosis of AIDS; Group B, of patients without HIV infection, and group C of patients with asymptomatic HIV infection. Patients with any known predisposing factor for UTI were excluded from the study. A clean-catch midstream urine sample was collected from each patient on the first day of hospital admission (groups A and B) or during a visit to the outpatient clinic (group C). Bacteriuria was diagnosed when > or = 100,000 colony forming units/ml, urine were grown. RESULTS--There were 415 patients, 151 in group A, 170 in group B and 94 in group C. Bacteriuria was significantly more frequently in group A (20 cases, 13.3%) than in groups B (3 cases, 1.8%, p = 0.00007) and C (3 cases, 3.2%, p = 0.009). Ten cases of bacteriuria in group A (6.6%) were symptomatic while no case of symptomatic UTI was seen in groups B (p = 0.0004) and C (p = 0.008). The frequency of UTI in homosexual men with AIDS (7 cases, 6.7%) was not significantly different from that observed in men with AIDS who denied homosexuality (3 cases, 6.5%). E coli was the predominant pathogen associated with UTI. Although adequate response to a two-week course of antibiotics was observed in most cases, an in-hospital mortality rate of 20% was found among AIDS patients with symptomatic UTI. CONCLUSIONS--In the present study, the frequency of bacteriuria and symptomatic UTI was found to be increased in men with AIDS. E coli was the predominant pathogen in these cases. These data suggest that symptomatic UTI may represent a relevant cause of morbidity for men with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1994

Reclassifying physicians as employees for Federal tax purposes.

The Internal Revenue Service is attempting to reclassify many physicians as hospital employees rather than as independent contractors. Reclassifying physicians as employees could leave thousands of physicians and hospitals facing costly employment tax audits and owing millions of dollars in back taxes and penalties. In addition, some hospital pension and benefits plans that have misclassified physicians could be invalidated, and substantial penalties could be imposed on hospitals.

Contract Services↗
PubMed1993

Differential OMP expression in opossum accessory olfactory bulb.

Using immunohistochemical techniques, olfactory marker protein (OMP) was localized to the main (MOB) and accessory (AOB) olfactory bulbs of 30- and 45-day-old, and adult Brazilian opossums, Monodelphis domestica. Entire olfactory nerve and glomerular layers of the adult opossum MOB were darkly stained. In the adult AOB the rostral half of these two layers was stained more intensely than the caudal half, and both parts were less darkly stained than the MOB. This differential AOB staining was not present at 30 days of age, but was evident by postnatal day 45, although not as dramatic as in adults. This is the first report of differential OMP expression and may provide an approach to identifying the function of OMP.

Aging↗
PubMed1993

Developmental changes in cytochrome oxidase histochemistry in the main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis spp.).

Developmental studies examining the changes in oxidative metabolic activity are useful for understanding how and if the vomeronasal and olfactory systems respond to stimulation during embryogenesis. Garter snakes are good candidates for examining the potential functionality of the vomeronasal system in utero. In adult garter snakes, the vomeronasal system mediates many behaviors. Neonatal garter snakes exhibit these same behaviors, and the vomeronasal system has been shown to mediate feeding behavior in neonates. Using cytochrome oxidase histochemistry, we examined changes in the oxidative metabolic activity of main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis sirtalis and T. s. parietalis). Cytochrome oxidase staining is greater in the accessory olfactory bulb than in the main olfactory bulb of embryonic garter snakes. However, neonates show no differences in the staining of the accessory and main olfactory bulbs, suggesting a change in the stimulation of the main olfactory bulb after birth. This is the first report of cytochrome oxidase histochemistry in reptiles and in the vomeronasal system of embryonic vertebrates.

Aging↗
PubMed1993

Nuzzling in the gray short-tailed opossum. I: Delivery of odors to vomeronasal organ.

Nuzzling in the gray short-tailed opossum (Monodelphis domestica) is exhibited in response to conspecific odor deposits and is involved in chemosensory recognition. Nuzzling consists of bouts of repeated forward rubbing motions (with intermittent tapping) with the ventral aspect of the snout over the odor source, while moistening it with naso-oral secretions. The role of nuzzling in odorant d delivery to the vomeronasal organ (VNO) was investigated. Five opossums were allowed to nuzzle conspecific odor deposits mixed with 3H-proline. Histological sections of the snouts processed for autoradiography revealed very strong labeling of the VNOs, primarily the nonsensory epithelium. No labeling was observed in the olfactory epithelium. Unilateral closure of the oral opening to the nasopalatine canal resulted in labeling of the contralateral VNO only, implicating oral access to the VNO. Several distinctive structures appear to be associated with chemical access. An experiment in which 16 males and 16 females were given a preference test of dried nuzzling secretion versus dried distilled water established that the naso-oral secretions deposited during nuzzling do not have properties of scent marks.

Animal Communication↗
PubMed1993

Nuzzling in the gray short-tailed opossum. II: Familiarity and individual recognition.

Nuzzling is a chemosensory exploratory behavior that enables South American gray short-tailed opossums to dissolved dry conspecific odor deposits in naso-oral secretions and incorporate them into their vomeronasal organs. This report documents that male opossums nuzzle novel (unfamiliar conspecific) male odors significantly longer than familiar (own of familiar conspecific) male odors or clean substrates. Such findings suggest that an important ethological function of nuzzling behavior involves individual recognition of conspecifics. The first experiment demonstrates that a very short (3-min) exposure to a conspecific odor is sufficient to establish familiarity. The second experiment reveals that a brief exposure results in prolonged (at least 2 h) odor retention. Both experiments establish that nuzzling by males is normally followed by scent marking; thus, novel male odors also elicit increased scent marking. We have identified four novel forms of scent marking by male Monodelphis domestica (ventral, chin, anal/cloacal, and neck) and our data suggest that marking style may be at least partially dependent on the physical properties of the substrata.

Animal Communication↗
PubMed1993

Electrophysiological analysis of the nasal chemical senses in garter snakes.

Electroolfactogram and electrovomeronasogram recordings were made from garter snakes stimulated with vapor of amyl acetate, butanol and of earthworm wash. The olfactory epithelium was more sensitive than the vomeronasal epithelium to all three stimuli. Volatiles from prey washes were capable of stimulating the olfactory epithelium when delivered as airstreams. The vomeronasal epithelium was sensitive only to the air delivery of vapor of amyl acetate. Single unit recordings from the mitral cell layer of the accessory olfactory bulb of garter snakes were made in response to liquid delivery of a variety of chemical stimuli including classical odorants, amino acids and proteins derived from prey. All three classes of stimuli altered unit firing in the accessory olfactory bulb. Amyl acetate, earthworm wash, goldfish wash and non-volatile amino acids delivered as liquid stimuli to the vomeronasal epithelium produced responses in the accessory olfactory bulb that were more distinct and reliable than the electrovomeronasogram responses to airborne odorants recorded at the periphery. Both excitatory and inhibitory responses were observed in the accessory olfactory bulb of garter snakes. The direction of the response to a given stimulus differed for different neurons. Responses were frequently biphasic and could last longer than 50 seconds. Individual neurons responded to different classes of stimuli suggesting that they are broadly tuned.

Animals↗