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Biomedical subjects

P Katz

Publications and source records attributed to P Katz.

At least 73 records · Page 4Linked to original sources
PubMed1989

Suppression of B cell responses by natural killer cells is mediated through direct effects on T cells.

We examined the ability of human natural killer (NK) cells to modulate T cell-dependent mitogen-induced B cell responses. Highly purified NK cells inhibited the polyclonal antibody responses of autologous pokeweed mitogen (PWM)-stimulated unfractionated mononuclear cells in a reverse hemolytic plaque-forming cell (PFC) assay. Investigation of the possible mechanism(s) of the suppressor activity of NK cells revealed that lysis of mitogen-stimulated cells was unlikely. Chromium-51 release cytotoxicity assays of PWM-stimulated mononuclear cells did not demonstrate lysis by NK cells. Additionally, the monoclonal antibody 13.3, which abrogates NK cell cytolysis, did not reverse NK cell-dependent suppression of PFC formation. The putative lytic molecule elaborated by NK cells, NK cytotoxic factor, did not suppress B cell responses, further supporting a nonlytic inhibitory mechanism. That NK cell-derived lymphokines such as IFN-alpha, IFN-gamma, or IL-2 were uninvolved in the down-regulation of B cells was corroborated by the failure of antibodies to these mediators to reverse the suppression. NK cells did not suppress PFC formation when T cells were replaced by supernatants from PWM-stimulated T cells; additionally, NK cells had no effect on the generation of these necessary T cell factors. However, the coculture of T cells with NK cells resulted in the induction of suppressor activity within the T cell population suggesting that this was the mechanism of NK cell-mediated suppression of B cell responses.

Antibody Formation↗
PubMed1989

Sickled cells in synovial fluid: clue to unsuspected hemoglobinopathy.

In this report, we have described three patients who had hemarthroses, with sickled red blood cells discovered by analysis of synovial fluid. On the basis of this observation, each patient was evaluated for the presence of abnormal hemoglobins, and each was found to have a hemoglobinopathy that was previously unsuspected. These patients differ from those in other reports in that two of the three had no associated arthritic condition that could readily explain synovitis or a condition that predisposed them to bleeding into a joint. Although the accumulated evidence suggests that heterozygous hemoglobinopathies do not produce arthritic syndromes, these reports again raise that question. We cannot conclude, however, that the hemarthroses were definitively caused by the underlying hematologic abnormality. Important when synovial fluid is mixed with blood, since other medical conditions can be diagnosed if abnormal findings are detected.

Aged↗
PubMed1989

Disseminated neisserial infection in pregnancy: the empress may have a change of clothing.

A case of disseminated neisserial disease during pregnancy with good perinatal outcome is presented along with two examples of disseminated N. meningitidis from endocervical site. Upon close review, it is clear that the biological similarities of both N. gonorrhoeae and N. meningitidis may outweigh their differences. The two organisms may behave in clinically indistinguishable fashion and probably justify a more cautious approach to the clinical syndromes we have considered the inviolate domain of the gonococcus. The management of disseminated neisserial disease in pregnancy should include prompt empiric parenteral therapy while aggressive diagnostic confirmation of the organism is pursued. In addition, neonatal conjunctivitis caused by a Gram-negative diplococci should be treated parenterally until clinical response and identity of the organism is confirmed.

Adult↗
PubMed1988

Growth hormone releasing factor and somatostatin concentrations in the milk of lactating women.

The concentrations of growth hormone releasing factor (GRF) and somatostatin, two hypothalamic neuropeptides involved in the regulation of growth hormone secretion, were measured in human milk samples. The study was performed in healthy women within 48 h of delivery or during established lactation (between 1 and 64 weeks post delivery). No statistically significant correlation was found between the levels in milk of either of the neuropeptides and the gestational age at birth. However, lower values of GRF (23 +/- 4.7 pg/ml vs. 40.5 +/- 4.9 pg/ml) were found in milk obtained during established lactation than in milk obtained close to delivery. A positive correlation was observed between somatostatin and GRF concentrations in milk. The possible involvement of milk neuropeptides in the control of growth hormone secretion in the neonate, as well as in the regulation of other physiological processes, are evaluated.

Adolescent↗
PubMed1988

Traditional thought and modern Western surgery.

This study, based in part on anthropological field work with surgeons, is an examination of some aspects of traditional thinking and practices which coexist with, and are embedded in, the scientific thinking and practices of modern surgery. The focus is on the role of these beliefs and practices in modern surgical culture in understanding the causes and prevention of post-operative infections. Three beliefs and practices that exist in traditional and modern medical systems are examined: (A) personalistic disease causes and cures; (B) myriad endogenous and exogenous disease causes; and (C) ritual practices. The adaptive and nonadaptive functions of these beliefs and practices in modern surgery are explored.

Anthropology, Cultural↗
PubMed1988

Novel interleukin 2 (IL-2) receptor appears to mediate IL-2-induced activation of natural killer cells.

A novel IL-2 receptor, distinct from the Tac protein, has been identified on the surface of purified human natural killer (NK) cells by chemical cross-linking of 125I-IL-2. This protein is approximately 70,000 D in size (p70) and appears to be identical to the recently recognized second subunit of the human high affinity IL-2 receptor complex. Scatchard analysis of 125I-IL-2 binding to purified NK cells revealed approximately 2,300 p70 binding sites per cell with an apparent dissociation constant of 200 pM, a value intermediate between the previously recognized high and low affinity forms of the human IL-2 receptor. The monoclonal anti-Tac antibody did not inhibit the cross-linking of 125I-IL-2 to the p70 binding sites present on NK cells. Functionally, the addition of high concentrations of recombinant IL-2 to the enriched NK cells promoted a rapid augmentation of cytolytic activity and a more delayed increase in cellular proliferation. Anti-Tac effectively blocked the IL-2-induced proliferative response in these cells, but failed to alter the enhancement of cytotoxicity. Analysis of NK cytoplasmic RNA isolated at various time points after IL-2 stimulation revealed the rapid induction of c-myb and Tac gene expression that was also not inhibited by the anti-Tac antibody. These findings suggest that IL-2 binding to the p70 receptor constitutively expressed on the surface of NK cells may mediate both the development of increased cytolytic activity and rapid changes in gene expression. The activation of the Tac gene may in turn permit the formation of the high affinity IL-2 receptor complex (comprised of at least the Tac and p70 proteins) that appears to transduce the requisite signals involved in NK cell proliferation.

Antigens, Surface↗
PubMed1987

Detection of Duchenne muscular dystrophy carriers: quantitative echography and creatine kinasemia.

Data obtained from simultaneous determinations of serum creatine-kinase levels and estimation of ultrasound attenuation values in muscles greatly improved the detection of obligate carriers of Duchenne muscular dystrophy than when only one of these methods was employed alone. Eleven carriers out of 19 had a high creatine-kinasemia level and nine carriers out of 19 had a high (abnormal) attenuation value. Because of the limited overlapping between the two parameters studied, we were able to recognize 17 obligate carriers out of the 19. This indicates that the parameters studied concern different features of the disease, and the practical and theoretical considerations are discussed. The techniques are discussed together with molecular genetic investigations.

Adult↗
PubMed1987

Technetium pyrophosphate muscle scans in inflammatory muscle disease.

Technetium-99M pyrophosphate (TcPYP) nuclear scans of extremities were performed on 15 patients at 10 minutes and 2 hours after isotope injection. Scans were carried out both to confirm the diagnosis of myositis and to direct subsequent muscle biopsy. Five of six patients with clinical features strongly suggestive of inflammatory muscle disease had positive scans. All muscle biopsies performed at areas of increased isotope uptake showed inflammatory muscle disease. All nine patients not suspected of active inflammatory muscle disease had negative scans. Two of these underwent muscle biopsy with negative results. Our observations suggest that TcPYP muscle scans may be useful both to confirm the clinical suspicion of inflammatory muscle disease and in directing the choice of site for muscle biopsy.

Biopsy↗
PubMed1987

Adrenal cortical adenoma and adrenal medullary hyperplasia of the right adrenal gland--a case report.

The normal adrenal gland contains two types of tissue, the adrenal cortical tissue and the adrenal medullary tissue. The cortex is divided into three portions: the outermost "zona glomerulosa," the central "zona fasciculata," and the innermost "zona recticularis." The adrenal medulla is a developmentally separate organ, derived from neuroectoderm, and is the site of epinephrine and norepinephrine production. Adrenal cortical adenoma is commonly the result of a basophilic tumor of the anterior pituitary that secretes excessive amounts of ACTH. Adrenal medullary hyperplasia (or pheochromocytoma) are clinically hazardous tumors because of their excessive secretion of catecholamines. Combined adrenal cortical adenoma and adrenal medullary hyperplasia of the right adrenal gland has never been described previously.

Adenoma↗
PubMed1987

Granulomatous musculoskeletal disease: sarcoidosis versus tuberculosis.

A patient with systemic sarcoidosis insidiously developed tuberculous arthritis. The concurrence of these diagnoses in any individual patient is rare. Musculoskeletal features of sarcoidosis and tuberculosis are reviewed, and the importance of obtaining appropriate cultures to differentiate these granulomatous disorders is illustrated.

Adult↗
PubMed1986

Use of an electronic stimulator for the treatment of dry mouth.

This paper presents an innovative approach to the treatment of xerostomia through normal physiologic mechanisms with a device that provides electrical stimulation to the oral and pharyngeal afferent nervous system; the result is a reflex volley of efferent impulses to the salivary glands, causing salivation. The device has been successful in treating xerostomic patients regardless of the etiology of their dry mouths.

Animals↗
PubMed1986

[Female transmitters of Duchenne's myopathy: detection by quantitative ultrasonography combined with blood creatine kinase].

Duchenne muscular dystrophy (DMD) is a disease inherited in an X-linked recessive manner. Nothing is yet known about the gene defect involved. The problem of DMD carrier detection is very important and now without satisfactory solution. Presently the best method, for this detection, is the determination of the serum creatine-kinase (CK) level. However about 30% of DMD children's mothers have normal CK levels. In this study we associated CK determination and a new echographic method. This physical investigation is based on the muscle attenuation measurements through the evolution of the running spectral moments. The parameter expressed is the slope of the ultrasound attenuation signal (in decibels by centimetre and by megahertz; dB . cm-1 . MHz-1). We measured this parameter in vivo on the vastus medialis. The use of the chemical technique and of the physical one improves largely the detection of obligate carriers of Duchenne muscular dystrophy than when one of these methods is employed alone. One such combination recognizes 17 out of the 19 obligate carriers in our series. The difference of the results obtained by these two unrelated methods cannot be yet interpreted, but can reflect genetic heterogeneity in DMD and the inactivation of the X chromosomes.

Creatine Kinase↗