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Biomedical subjects

I Goldberg

Publications and source records attributed to I Goldberg.

286 records · Page 16Linked to original sources
PubMed1970

Biogenesis of chloroplast membranes. IV. Lipid and pigment changes during synthesis of chloroplast membranes in a mutant of Chlamydomonas reinhardi y-1.

The glycolipid, phospholipid, pigment, and fatty acid content in whole y-1 cells during the greening process have been investigated. The time course of their changes indicates that phosphatidyl glycerol and glycolipids are the main lipids synthesized specifically during illumination of dark-grown cells, concomitant with an increase in the polyunsaturated C18:2 and C18:3 fatty acids. The pigment complex of light-grown cells consists mainly of chlorophylls a and b, lutein, beta-carotene, violaxanthin, and neoxanthin. During the greening process, chlorophylls a and b are synthesized in constant proportions (ratio a/b equals 2.6), beta-carotene and violaxanthin do not change significantly, and lutein and neoxanthin increase. The molar ratios of the different lipids and pigment to total chlorophyll during greening has been calculated. It was found that during the initial phase of greening when chlorophyll is synthesized at increasing rates, the molar ratios of various lipids and pigments to chlorophyll decrease and tend to become constant when chlorophyll and membrane synthesis proceed at constant rates. The implication of these findings with respect to the concept of membrane assembly through a spontaneous single step process is discussed

Acetates↗
PubMed1970

Biogenesis of chloroplast membranes. V. A radioautographic study of membrane growth in a mutant of Chlamydomonas reinhardi y-1.

The development of photosynthetic lamellae during greening of dark-grown Chlamydomonas y-1 cells was investigated by radioautography. Acetate-(3)H was used as a marker for membrane lipids. In short pulse-labeling experiments, about 50-60% of the radioactivity incorporated was found in the lipid fraction and about 25-50% in starch granules present in the chloroplast of these algae. The relative specificity of acetate-(3)H used as a marker for membranes was artificially increased through quantitative removal of the starch granules from fixed cells by amylase treatment. Analysis of turnover coefficients of different membrane constituents and of the contribution of turnover and net synthesis to the total label incorporated in pulse experiments indicated that the incorporation of acetate into specific lipids was mainly due to net synthesis. The distribution of radioactivity in the different lipid constituents at the end of a short pulse and after 30- and 60-min chases indicated that transacylation is minimal and may be disregarded as a possible cause of randomization of the label. Statistical analysis of radioautographic grain distribution and measurements of different structural parameters indicate that (a) the chloroplast volume and surface remain constant during the process, whereas the growth of the photosynthetic lamellae parallels the increase in chlorophyll; (b) the lamellae do not develop from the chloroplast envelope or from the tubular system of the pyrenoid; (c) all the lamellae grow by incorporation of new material within preexisting structures; (d) different types of lamellae grow at different rates. The pyrenoid tubular system develops faster than the thylakoids, and single thylakoids develop about twice as fast as those which are paired or fused to grana. It is concluded that growth of the membranes occurs by a mechanism of random intussusception of molecular complexes within different types of preexisting membranes.

Autoradiography↗
PubMedDate not supplied

Compliance with ocular therapy.

Patient noncompliance with the physician's prescribed therapeutic regimen can present serious obstacles both to individual patient care and to the obtaining of information necessary for controlled drug trials. Unfortunately, the physician often is unable to determine whether and to what extent a patient is not complying with therapy. This article reviews the problem of patient noncompliance with particular emphasis on how and why noncompliance occurs, and methods of predicting, detecting and coping with the defaulting patient.

Eye Diseases↗
PubMedDate not supplied

Relation of preexisting anti-beta2GPI antibodies to infarct size in a rat model.

BACKGROUND: Anti-beta2-glycoprotein I (beta2GPI) antibodies (a subpopulation of antiphospholipid (aPL) antibodies) are associated with a procoagulant state in humans and with enhanced atherosclerosis in experimental animal models. Moreover, the presence of high titers of aPL antibodies in relatively young patients is associated with higher incidence of subsequent myocardial infarction. Herein, we evaluated the role of preexisting high levels of aPL antibodies in determining the size of the infarct induced by permanent ligation of the left anterior descending artery (LAD) in a rat model. METHODS AND RESULTS: A total of 11 Wistar rats were immunized and boosted with 10 microg of the phospholipid binding protein -beta2GPI (a method commonly applied for induction of aPL antibodies). Rats in the control group (n=9) were immunized and boosted with a Freund's adjuvant. Upon development of high anti-beta2GPI antibodies levels, myocardial infarction was induced by ligation of the LAD coronary artery. Rats were sacrificed 7 days later, their lymph nodes were collected for evaluation of cellular immunity to beta2GPI and their hearts were removed for assessment of infarct size and for immunohistochemical stains for iNOS and TGF-beta. beta2GPI-immunized rats exhibited high levels of aPL antibodies (mean optical density of 1.3+/-0.3) as compared with the control group (mean optical density of 0.12+/-0.03; P<.0001). Cellular immunity to beta2GPI was also pronounced as evident by an increased thymidine uptake and by increased interferon gamma secretion by the lymph node cells from beta2GPI-immunized rats. Myocardial infarct size has shown a tendency to be increased in rats induced to develop anti-beta2GPI antibodies (mean size 23+/-9%) as compared with controls (17+/-12%; P<.23). iNOS positive cells in the infarct area of beta2GPI-immunized rats were significantly increased in comparison to the control group (P<.01). Similarly, TGF-beta cell expression was significantly increased in the infarct area of the immunized rats in comparison to the control group (22.6+/-5.1 and 7+/-2.1 per 100 mononuclear inflammatory cells, respectively; P=.01). CONCLUSION: The presence of high levels of aPL antibodies is associated with higher expression of iNOS and TGF-beta and may contribute to myocardial damage.

Animals↗
PubMedDate not supplied

Recurrent dislocations of the hip in a child presenting as nocturnal pains.

Nocturnal pains of the leg were the only complaint of a 2 1/2-year-old girl with recurrent dislocations of the left hip. Unusual movement during sleep probably caused the dislocations. This case represents a benign entity characterized by spontaneous or voluntary posterior dislocations of the femoral head in young children without other significant connective tissue abnormalities.

Child, Preschool↗
PubMedDate not supplied

Analyses of p53 expression pattern and BRCA mutations in patients with double primary breast and ovarian cancer.

OBJECTIVE: To analyze the somatic pattern of p53 expression and BRCA germline mutation status in Israeli patients with both ovarian (OvCa) and breast cancer (BrCa). METHODS: The study group comprised 43 Israeli patients with OvCa, all of whom had previous primary BrCa. p53 immunohistochemistry (IHC) on all available archival tissues and genotyping for the three predominant Jewish germline BRCA1-2 mutations were carried out. Samples from 64 patients with solitary OvCa and 61 with solitary BrCa were similarly analyzed as controls. RESULTS: p53 expression pattern and the immunopositivity rate were similar in the ovarian and breast tumors within the study group and in the two control groups: positive p53 staining was detected in 68% of ovarian tumors in the study group compared with 71.9% in the controls, and in 19.4% of the BrCa tissues versus 21.3% in the controls. Within the study group, advanced stage OvCa had a higher rate of p53 expression (84%) compared to early stage disease (38.5%) (P = 0.006). This difference was not apparent in the solitary OvCa control group. OvCa in BRCA1-2 mutation carriers from the study group were more likely to display positive p53 staining (79%), especially in tumors diagnosed before the age of 60 (90%) compared with the OvCa of noncarriers (60%), but this difference was statistically insignificant. The p53 expression rate in BrCa samples from the study group was not associated with BRCA1-2 mutation status. CONCLUSIONS: Positive p53 expression, detected by IHC, in OvCa patients with previous primary BrCa is significantly higher in advanced stage disease in BRCA1-2 mutation carriers. There is a higher positive p53 expression somatically in OvCa in BRCA1-2 carriers in whom OvCa was diagnosed before the age of 60 years, although this trend is not statistically significant. These observations suggest that somatic p53 inactivation may be an important event in ovarian tumorigenesis in this subset of patients.

Aged↗
PubMedDate not supplied

Valvular deposition of antiphospholipid antibodies in the antiphospholipid syndrome: a clue to the origin of the disease.

In this report we present an unusual case of a 45-year-old female patient with systemic lupus erythematosus (SLE) who was hospitalized for mitral valve replacement. In her childhood she presented with mitral stenosis and chorea on which grounds a preliminary diagnosis of rheumatic fever was established. After a quiescent period lasting two decades her disease erupted with mitral stenosis, thromboembolic phenomena, and nephritis. Due to severe malfunctioning of her mitral valve, the patient eventually underwent mitral valve replacement. The antibodies involved in the pathogenesis of our patient's valvular disease were studied by immunohistochemical analysis, applying rabbit polyclonal anti-human IgG and IgM anti-human C3c and anti-idiotypes to a mouse monoclonal naturally occurring polyspecific human monoclonal anti-cardiolipin antibody termed S2.9, and to the 16/6 Id which defines a common Id on anti-DNA antibodies in patients with SLE. Immunoperoxidase staining using an anti-idiotype mAb to anti-cardiolipin antibodies demonstrated the deposition of these anti-bodies in the subendothelial layer of the valve. We believe that anti-phospholipid syndrome (APS) with SLE was the initial and primary disease in this patient. These findings clearly indicate that APS must be considered in the differential diagnosis of rheumatic fever, particularly in young female patients who present with mitral stenosis and chorea.

Adolescent↗
PubMedDate not supplied

Neonatal osteomyelitis of the calcaneus following a heel pad puncture: a case report.

Osteomyelitis of the calcaneus developed in a 6-day-old girl subsequent to heel pad puncture for taking blood samples. A review of the literature indicates that as a complication, osteomyelitis is very rare, considering the thousands of punctures performed. There is no mention in the orthopedic literature of such cases being treated in neonatal units. The present case, like others reported thus far, is characterized by the benign course of the disease. Theoretically, it is possible that infectious process could spread from the heel primary site to other bones or joints. Some difficulty in early diagnosis may be encountered in the incipient stages of the disease because of the benign course and lack of radiologic findings. In such cases, when local findings and the history of heel pad punctures suggest an infectious process involving the bone, a bone scan is helpful inasmuch as it is positive before the radiologic signs become manifest. An adequate course of antibiotic therapy, immediately administered, is usually successful, with normal X-ray of the healed os calcis being evident after two to three months. Nevertheless, prophylactic therapy is strongly recommended.

Anti-Bacterial Agents↗
PubMedDate not supplied

Postgraduate medical education and flexible training.

The importance of opportunities to train and work on a flexible basis are emphasized, particularly in the light of current medical staffing shortages in the NHS and the need to use resources effectively. The profile of the medical workforce is very different now compared with 40 years ago, and career pathways must therefore be modified.

Education, Medical, Graduate↗
PubMedDate not supplied

New approaches to job-sharing of training posts in the North Thames region.

This paper proposes a new way of managing the provision of flexible training opportunities by job-sharing. It shows how the difficulties of implementing job-sharing can be overcome, and gives an example of implementation of job-sharing in the context of flexible training.

Education, Medical, Graduate↗