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Biomedical subjects

R A Greene

Publications and source records attributed to R A Greene.

29 records · Page 2Linked to original sources
PubMed1986

MURCS association with additional congenital anomalies.

The postmortem findings in a patient with the MURCS association (müllerian duct aplasia/hypoplasia, renal agenesis or ectopy, and cervicothoracic somite dysplasia) are reported. This is the first autopsy study since the syndrome was recognized. The autopsy revealed abnormalities of the venous, pulmonary, and central nervous systems that had not been reported previously in patients with this syndrome. A review of the literature suggested that although the MURCS association usually occurs sporadically, as in this case, a familial association is occasionally present. In some cases the MURCS association may be a genetically determined pleiotropic condition.

Abnormalities, Multiple↗
PubMed1981

Results of argon laser exposure of capillary hemangiomas of infancy--preliminary report.

Argon laser photocoagulation of capillary hemangiomas of infancy ("strawberry marks") has been described in three cases. Treatment in the first case was necessitated by repeated alarming hemorrhage. The second case was treated totally and resulted in immediate induced resolution of the hemangioma, which preceded (by 9 months) the spontaneous involution of an untreated control comparison area and resulted in virtually complete blanching without secondary deformity. The third case demonstrated the laser's ability to stop rapid growth immediately. Spontaneous involution then ensued naturally and was complete 12 months later. It should be emphasized that the argon laser is not recommended for the routine treatment of a normally spontaneously involuting hemangioma. Each case must be examined and the usual indications for intervention should be present. The argon laser has demonstrated the ability to coagulate vascular lesions such as port wine hemangiomas and telangiectasias and can be expected to have a similar favorable effect on the aggressive, rapidly expanding juvenile hemangioma, although further clinical documentation clearly remains to be demonstrated.

Argon↗
PubMed1975

Translation of silk fibroin messenger RNA in an Ehrlich ascites cell-free extract.

RNA identified by its base composition and T1 RNase oligonucleotide pattern as the message for silk fibroin was purified from mature posterior silk glands of Bombyx mori larvae and used to direct polypeptide synthesis in an Ehrlich ascites cell-free extract. Fibroin mRNA stimulated [3-H]alanine incorporation about 3- to 4-fold in the presence of 80 mM K+ and 4 mM Mg-2+. The stimulation was reduced in the presence of 5 times 10-minus 6 to 10-minus 4 M aurintricarboxylic acid, an inhibitor of the initiation of protein synthesis. The cell-free products were heterogeneous in size, including peptides as large as 100,000 daltons. They co-precipitated with carrier fibroin sequences after digestion with trypsin. A large fraction of the polypeptides synthesized in response to fibroin mRNA was precipitated by antiserum directed against amino acid sequences in noncrystalline region polypeptides of fibroin. Furthermore, after digestion with chymotrypsin, a major fraction of the cell-free products specifically co-precipitated with crystalline region sequences of native fibroin. The size and amino acid composition of the fibroin crystalline region polypeptides isolated from the cell-free products were similar to those from native fibroin.

Amino Acids↗
PubMed1972

Effect of carbon source on size and associated properties of Bacillus megaterium spores.

The size of the spores produced by Bacillus megaterium ATCC 19213 depended upon the nature of the carbon source present in the defined medium in which they were produced. Homogeneous preparations of small (0.38 mum(3)), nearly spherical spores were produced after batch culture in the presence of 2.8 mm citrate, and large (1.17 mum(3)), oblong spores were produced by replacement culture in the presence of 7.35 mm acetate. Large and small spores had approximately the same deoxyribonucleic acid content, density, and heat resistance. Large spores contained about 2.5 times the dipicolinic acid, glucosamine, ribonucleic acid, Mn(2+), and lipid and about 1.5 times the Mg(2+), Fe(2+), Ca(2+), and dry weight of small spores. Large spores were especially enriched in Zn(2+) (4.5-fold). More protein (1.5-fold) was extracted from small spores with 1 n NaOH than from large spores, possibly indicating a difference in the spore coats, but large spores contained about twice the Kjeldahl nitrogen of small spores. A difference in the coats may account for the fact that, unlike small spores, large spores showed improved germination with increased times and temperature of heat shocking. The possibility of determining the location of some of these substances within the spore by comparing the compositional ratios with estimated volumes of specific spore layers is discussed.

Acetates↗
PubMed1972

Minimal requirements for commitment to sporulation in Bacillus megaterium.

Commitment to sporulation was examined by means of both endotrophic sporulation and rejuvenation experiments. In both cases, a point of commitment to the completion of sporulation occurred at stage II. With 2 x 10(8) cells/ml, the process by which commitment occurred required 0.5 mm Mg(2+), 10.0 mm phosphate, and an energy source (minimum of 5.0 mm acetate). For completion of sporulation and formation of normal, heat-resistant refractile spores, 0.3 mm Ca(2+) was required. Except for this Ca(2+) requirement, the completion of sporulation after commitment was independent of the nature of the surrounding medium. Some aspects of the utilization of these required substances were examined.

Acetates↗
PubMedDate not supplied

Multiple test analyzer (MTA): a microcomputer program for determining preferred strategies with two diagnostic tests.

There are ten distinct management strategies in clinical situations that involve two diagnostic tests with dichotomous outcomes. The authors describe a microcomputer program, based on a previously described model, that can be used to identify test and test-treatment thresholds and to compute preferred strategies. The program provides tables and graphs of the results, which can be viewed or printed, and there is an optimization routine that facilitates comprehensive analysis. It can be used by decision-analytic researchers and policy analysts, medical educators who teach decision analysis, and clinicians who use decision analysis in their practices.

Computers↗
PubMedDate not supplied

Estrogen and cerebral blood flow: a mechanism to explain the impact of estrogen on the incidence and treatment of Alzheimer's disease.

OBJECTIVE: Women are three times as likely to develop late-onset Alzheimer's Disease (AD) as are age-matched men. In the perimenopausal period, women typically have profound hypoestrogenism associated with vasomotor episodes. The pattern of AD development in women resembles the hormonal changes that occur in the perimenopausal period; the risk of AD is lower in menopausal women taking estrogen replacement therapy (ERT), and ERT is associated with clinical improvement in AD patients. Further, ERT has been shown to augment the therapeutic benefits of medications designed to treat AD. To understand better the relationship between ERT, hot flushes and AD, a pilot study was conducted at UCLA-Harbor Medical Center. PATIENTS AND METHODS: Twelve healthy menopausal women experiencing daily hot flushes and not on ERT were recruited to participate in a clinical study. Each patient underwent regional cerebral blood flow (CBF) measurement using single-photon emission computed tomography (SPECT) at baseline and during a hot flush episode. Patients were then randomized to receive either 0.625 mg or 1.25 mg conjugated equine estrogens (CEE) daily. During the sixth week of ERT, each patient had a repeat SPECT study. Baseline SPECT data were compared with ERT data. RESULTS: Baseline examinations demonstrated CBF patterns commonly seen in patients with Alzheimer's disease. There was a global improvement in CBF associated with ERT, an average gain of 22% over baseline. Improvements were most dramatic in the temporal and parietal regions of the brain. The cortical CBF demonstrated a mean increase of 9.2 mL/100 g/min (P < .01). CONCLUSIONS: CBF is diminished in hypoestrogenic women, with regional patterns resembling those of patients with mild to moderate AD. Cerebral circulation tends to be further compromised during hot flush episodes. This mechanism could be the initiating event in the metabolic process that results in dementia of the Alzheimer's type, and thus serve as the link between hypoestrogenism and neurodegenerative diseases. In this study, ERT reversed these detrimental blood flow changes back to a normal pattern after only 6 weeks of CEE therapy. With improved blood flow, the brain is protected from the metabolic injury associated with hypoxia. The study is currently being repeated with a larger population.

Adult↗
PubMedDate not supplied

The new genetic era in reproductive medicine: possibilities, probabilities and problems.

The "New Genetic Era" will be a period of enormous exponential growth in our knowledge of the structure and function of the basic information blocks of life. The Human Genome Project will soon provide a complete and accurate sequence of the human genome. This will give us an abundance of basic genetic knowledge and provide a molecular understanding of disease, allowing for improved diagnosis and more sensitive and specific screening for disease. This will, we hope, lead to better treatments, prevention and cures through gene therapy, patient-specific drug design, and earlier and more specific behavioral interventions to prevent disease. With this information comes a complexity of legal, ethical and social concerns about potential use and abuse. The public has expressed its concerns about the potential for genetic discrimination. However, genetic information is enhancing our knowledge as to the causes of infertility, allowing diagnosis of more diseases in the prenatal period, and may aid our identification of patients at increased risk for breast and ovarian cancer. Doctors involved in reproductive medicine must become knowledgeable about the new genetic era so as to offer our patients the most appropriate and informed care.

Cloning, Organism↗