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Biomedical subjects

R Weiss

Publications and source records attributed to R Weiss.

At least 307 records · Page 17Linked to original sources
PubMed1989

Regional myocardial O2 consumption and coronary blood flow responses to acetylcholine in rabbit heart.

The effect of acetylcholine on regional coronary blood flow and myocardial O2 consumption was determined in order to compare its direct vasodilatory effects with the metabolic vasoconstriction it induces. Experiments were conducted in seven untreated control anaesthetized open chest rabbits and seven rabbits which were infused with acetylcholine (1 microgram/kg/min). Myocardial blood flow was determined before and during acetylcholine infusion using radioactive microspheres. Regional arterial and venous O2 saturation was analyzed microspectrophotometrically. Acetylcholine reduced heart rate by 30% and significantly depressed the arterial systolic and diastolic blood pressure. The mean O2 consumption was significantly reduced with acetylcholine from 9.6 +/- 2.0 to 6.1 +/- 3.6 ml O2/min/100 g. Coronary blood flow decreased uniformly across the left ventricular wall by about 50% and resistance to flow increased by 42% despite potential direct cholinergic vasodilation. O2 extraction was not affected by acetylcholine infusion. It is concluded that the acetylcholine infusion directly decreased myocardial O2 consumption, which in turn lowered the coronary blood flow and increased the resistance. The decreased flow was related to a reduced metabolic demand rather than a direct result of lowered blood pressure. Unaffected myocardial O2 extraction also suggested that blood flow and metabolism were matched. This indicates that direct cholinergic vasodilation of the coronary vasculature does not allow a greater reduction in metabolism than flow in the anaesthetized open chest rabbit heart during acetylcholine infusion.

Acetylcholine↗
PubMed1989

Appealing to an important customer. Physicians should be the target of marketing.

Although many healthcare professionals are turning to the general public to increase market share and referrals, they should be directing their attention to physicians instead. One of the major challenges facing hospitals is determining physician needs. A survey may be necessary to identify physicians' perceptions, attitudes, values, expectations, market, and hospital loyalty. Another important research document is the physician profile, which includes each doctor by age, specialty, office location, admitting and outpatient referral activity, financial contribution, and referral and other affiliations. Surveying should not end with the physician. One of the best means of evaluating patient and physician satisfaction is by questioning physicians' office staff. To centralize physician services, a number of hospitals have established physician liaison programs, which bridge the gap between the hospital and the physician's office, heighten physician satisfaction, and increase referrals. Physician orientation is a key element of most outreach programs, providing an opportunity to develop relationships with new physicians. Other means of directly aiding physicians are physician referral services and practice enhancement and assistance.

Data Collection↗
PubMed1989

[The occurrence and significance of plasma coagulase negative staphylococci from the genital tract of horses].

Classification based on biochemical characteristics of 389 strains of plasma-coagulase-negative (plc-) staphylococci isolated from the genital tract of mares and stallions resulted in the following distribution of species: St. sciuri 130 (33.4%), St. equorum 42 (10.8%), St. xylosus 16 (4.1%), St. epidermidis 35 (9.0%), St. simulans 24 (6.2%), St. haemolyticus 33 (8.5%), St. warneri 18 (4.6%), St. lentus 12 (3.1%), St. hyicus 11 (2.8%). Strains of St. cohnii, St. capitis, St. gallinarum, St. saprophyticus and St. hominis have only been found sporadically (a. 1%). 48 (12.3%) strains could not be classified. With regard to species distribution of isolates from stallions and mares. 63.7% of the isolates from stallions belonged to St. sciuri and 9.3% to St. lentus, whereas in isolates of mares these species numbered only 24.9% and 0.4%, respectively. On the other hand the species St. equorum (14.9% vs. 6.8%), St. epidermidis (14.5% vs. 1.7%), St. haemolyticus (14.0% vs. 1.7%), St. warneri (7.7% vs. 0.8%) and St. xylosus (5.9% vs. 2.5%) predominated in mares. St. simulans was found occurring equally in mares and stallions (7.7% vs. 5.9%). Comparing the staphylococcal species of healthy mares and of mares which have not become pregnant after copulation no indication was found for a significant role of certain plc- staphylococci in infertility. All of the 389 isolates were tested for production of protein A, i.e. Fc-fragment binding receptors, using a microenzyme-assay with peroxidase-labelled rabbit immunoglobulin G. With this method cell-bound or extracellular Fc-receptors could not be detected in anyone of the plc- staphylococcal strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Microbiological development studies in a clinically healthy, closed primate colony (Macaca mulatta, Macaca arctoides) after the establishment of a Salmonella infection].

A case of a Salmonella infantis septicemia in a primate (Macaca mulatta) probably induced by shipment stress gave rise to microbiological examination of fecal samples from all animals of a since 1976 closed colony of Macaca mulatta and Macaca arctoides. During 3 investigations carried out in 3 week intervals salmonella-positive animals were separated immediately from the stock. At the first examination 3 of 52, and at the second 2 of 49 samples were found to be salmonella-positive. At the third series all of the remaining 47 animals proved to be salmonella-negative. All isolates were identified as S. infantis. Feeding of contaminated, dried prawns was suspected as the most probable source of infection. A simultaneous examination of 96 of the stool specimens revealed Y. enterocolitica in 4 samples. Additionally, electron-microscopy of pooled fecal samples (3 to 4 animals each) led to demonstration of corona-, adenovirus and small round virus-like particles in one pool each. Moreover, coronavirus-like particles could be detected in 7 of 13 (1st examination series), 5 of 15 (2nd series) and 1 of 13 pools (3rd series).

Animals↗
PubMed1988

On the mechanism of ribosomal frameshifting at hungry codons.

In a few, rather rare cases, frameshift mutant alleles are phenotypically suppressed during limitation for particular aminoacyl-tRNA species. The simplest interpretation is compensatory ribosome frameshifting at a "hungry" codon in the vicinity of the suppressed frameshift mutation. We have now tested this interpretation directly by obtaining amino acid sequence data on such a phenotypically suppressed protein. We used a plasmid-borne lacZ gene, engineered to be in the (+) reading frame. Its background leakiness is increased by two orders of magnitude during lysyl-tRNA limitation. The enzyme made under this condition has the amino acid sequence expected from the DNA sequence up to the first lysine codon, then shifts in the (-) direction to recreate the correct lacZ reading frame. The lysine is replaced by serine, presumably due to cognate reading of an overlapping AGC codon displaced by one base to the 3' side of the AAG codon. When the 3' overlapping codon is AGA or AGG, there is no ribosome frameshifting; when it is AGU (read by the same serine tRNA) there is frameshifting, although less efficiently than in the case of AGC. The mechanism of cognate overlapping reading contradicts more elaborate models that two of the authors have suggested previously. However, the possibility remains that there is more than one mechanism of ribosome frameshifting at hungry codons.

Amino Acid Sequence↗
PubMed1988

A persistent untranslated sequence within bacteriophage T4 DNA topoisomerase gene 60.

A 50-nucleotide untranslated region is shown to be present within the coding sequence of Escherichia coli bacteriophage T4 gene 60, which encodes one of the subunits for its type II DNA topoisomerase. This interruption is part of the transcribed messenger RNA and appears not to be removed before translation. Thus, the usual colinearity between messenger RNA and the encoded protein sequence apparently does not exist in this case. The interruption is bracketed by a direct repeat of five base pairs. A mechanism is proposed in which folding of the untranslated region brings together codons separated by the interruption so that the elongating ribosome may skip the 50 nucleotides during translation. The alternative possibility, that the protein is efficiently translated from a very minor and undetectable form of processed messenger RNA, seems unlikely, but has not been completely ruled out.

Amino Acid Sequence↗
PubMed1988

Group work with adolescent PKU girls and their mothers.

Group therapy was the method chosen for working with PKU girls and their mothers in improving their knowledge of maternal PKU and the prevention of unplanned pregnancies. It was found effective in relieving anxiety, and the importance of including the mothers in the group was critical.

Adolescent↗
PubMed1988

Fibroepithelial polyp in a child.

Only 15 cases of fibroepithelial polyp in children have been reported in the world medical literature. Clinical differentiation between this tumor and a malignant ureteral tumor is difficult and often results in unnecessary nephrectomy. We report the sixteenth case of a child with fibroepithelial polyp of the ureter. The lesion was resected, and the kidney was preserved. Optimum treatment of this lesion mandates renal preservation in children. The rationale for this recommendation is explored.

Child↗
PubMed1988

Anterior pituitary, adrenal, and gonadal hormones during cocaine withdrawal.

Plasma luteinizing hormone (LH), prolactin, testosterone, and cortisol levels were determined in 16 patients after hospital admission for cocaine abuse, during the course of 4 weeks of hospitalization, and before discharge. Hyperprolactinemia was found at admission (mean +/- SD, 27.5 +/- 10.2 ng/ml) and persisted until discharge (mean +/- SD, 28.7 +/- 10.8 ng/ml). Plasma LH, testosterone, and cortisol levels were within normal limits. These findings suggest that persistent elevation of plasma prolactin levels after cocaine withdrawal may reflect a chronic cocaine-induced derangement in neural dopaminergic regulatory systems.

Adult↗
PubMed1988

Ganglioglioma containing osseous tissue and neurofibrillary tangles.

A ganglioglioma involving the temporoparietal lobe in a 49-year-old patient displayed several unusual histopathologic features. A large central focus of osseous tissue that was found may have resulted from metaplasia of a mesodermal component of the lesion. In addition, occasional ganglioma cells showed neurofibrillary tangles and granulovacuolar changes. The presence of these cytoplasmic structures, usually seen in Alzheimer's disease and other degenerative conditions, within a ganglioglioma emphasizes the diverse settings in which such neuronal changes may occur and may provide clues to their pathogenesis.

Brain Neoplasms↗
PubMed1988

Hyperprolactinemia during cocaine withdrawal.

Plasma prolactin levels were determined for 8 patients (7 males and 1 female) who reported an average of 3.7 years of cocaine abuse. The mean prolactin level for these 8 patients 24 to 72 hours following admission to the hospital was 20.58 (S.E. +/- 3.2) ng/ml. Hyperprolactinemia (greater than 20 ng/ml) was detected in 4 patients and 3 others had high borderline prolactin levels. Only 1 patient had a normal prolactin value at the time of admission to the hospital. The mean prolactin level obtained prior to the patients' discharge from the hospital was 31.7 (S.E. +/- 5.3) ng/ml. Five of the 8 patients had an increase in prolactin levels between time of admission and discharge from the hospital. The mean increment in plasma prolactin levels for these 5 patients was 15.5 (S.E. +/- 4.2) ng/ml (P less than .02). Two patients who had significant hyperprolactinemia (greater than 50 ng/ml) at the time of discharge from the hospital reported self-administering the highest cocaine dose (6-8 gm per week) of the 8 patient cohort. Since cocaine blocks dopamine reuptake and prolactin secretion is regulated, in part, by dopaminergic inhibitory mechanisms, cocaine withdrawal may induce rebound supersensitivity of prolactin secretion. Findings obtained in this study suggest that cocaine-related derangements in prolactin secretion may be a biologic marker of a protracted cocaine abstinence syndrome.

Adult↗
PubMed1988

[Study of amino acid and carbohydrate metabolism of porcine strains of Haemophilus by thin layer chromatography].

The aim of the present study was to investigate porcine reference and field strains of the species Haemophilus (H.) pleuropneumoniae and H. parasuis, as well as H. Taxon "minor group" and Taxon C on their amino acid and carbohydrate metabolism by thin layer chromatography. The 17 reference strains studied showed almost identical results within the different species and taxa in both, amino acid and carbohydrate metabolism patterns. Based on a few differing enzymatic reactions a reduced species- and taxon-specific reaction pattern could be established, which included L-alanine, L-citrulline and L-threonine of the amino acids as well as D-ribose, alpha-D-xylose, mannitol, trehalose, beta-melibiose and alpha-lactose of the carbohydrates. This differentiation system allowed a reliable identification of 7 field strains whereas 4 additional ones, hitherto pre-classified as H. parasuis, could not be associated with any of the above species and taxa.

Amino Acids↗
PubMed1987

Synthesis, structure and spectroscopic properties of two models for the active site of the oxygenated state of cytochrome P450 [corrected].

Two dioxygen adducts of thiolato-iron(II) porphyrins, [K(222)][Fe(TPpivP)(SC6HF4)(O2)] 1a and [Na(18c.6)][Fe(TPpivP)(SC6HF4)(O2)] 2 were synthesized by reaction of O2 with five-coordinate, high-spin, cryptated alkali metal thiolato-iron(II) 'picket fence' porphyrinate. They were characterized by visible and infrared spectroscopy: lambda max (log epsilon) = 360 nm (4), 427 nm (4.69), 560 nm (3.69), 610 nm (3.40) for both compounds; v(16O-16O) = 1139 cm-1 in chlorobenzene and fluorobenzene for 1a and 2. Single crystals of composition [K(222)][Fe(TPpivP)(SC6HF4)(O2)].[K(222)](SC6HF4)(C 6H5Cl)(H2O) 1b were obtained by diffusion of pentane/xylene mixtures into chlorobenzene solutions of 1a at -5 degrees C. Single crystals of composition [Na(18c.6)][Fe(TPpivP)(SC6HF4)(O2)] were obtained by slow diffusion of pentane into benzene solutions of 2. Structures of 1b and 2 were studied at 20 degrees C (1b) and -100 degrees C (1b and 2). 1b: space group P2(1)/c (monoclinic), a = 16.806(5) A (1.6806 nm), b = 14.331(4) A (1.4331 nm), c = 52.000(15) A (5.2000 nm), beta = 92.95(2) degrees, V = 12.507 A3 (12.507 nm3), Z = 4, Dcal = 1.28 g.cm-3 (t = 20 degrees C). The final R1 factor was 0.085 for 5238 reflections having I greater than 3 sigma(I). 2: space group P2(1)/c (monoclinic), a = 13.107(3) A (1.3107 nm), b = 27.055(4) A (2.7055 nm), c = 25.029(4) A (2.5029 nm), beta = 96.84(2) degrees, V = 8812 A3 (8.812 nm3), Z = 4, Dcal = 1.18 g.cm-3 (t = -100 degrees C). The final R1 factor was 0.088 for 6587 reflections having I greater than 3 sigma(I). The iron atom is, in both compounds, bonded to the four porphyrinato nitrogens (Np), the sulfur atom of the axial thiolate and one oxygen atom of the axially end-on bonded dioxygen molecule. The average Fe-Np distance found in 1b [1.994(4) A, 0.1994 nm] is not significantly different from that found in 2 [1.993(3) A, 0.1993 nm]. The Fe-S bond length is 2.367(3) A (0.2367 nm) in 1b and 2.365(2) A (0.2365 nm) in 2. The Fe-O1 distances with the oxygen atom of O2 bonded to iron are respectively 1.837(9) A (0.1837 nm) and 1.850(4) A (0.1850 nm). The end-on bonded O2 molecule is disordered in both complexes 1b and 2.(ABSTRACT TRUNCATED AT 400 WORDS)

Binding Sites↗