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Biomedical subjects

J Katz

Publications and source records attributed to J Katz.

At least 433 records · Page 24Linked to original sources
PubMed1990

Screening for glaucomatous visual field loss. The effect of patient reliability.

Eighty-eight glaucoma patients and 252 normal subjects underwent C-30-2 testing on the Humphrey Field Analyzer. The effect of fixation losses, high false-positive and false-negative response rates on visual field test results was assessed using the mirror image method of detecting asymmetry across the horizontal meridian, and the Humphrey STATPAC pattern standard deviation (PSD) and mean deviation (MD). Glaucoma patients with poor fixation (greater than or equal to 20%) had less depressed fields and fewer localized defects than those with good fixation. Fixation loss did not affect measures of localized defects or generalized depression among normal subjects. High false-positive rates (greater than or equal to 10%) were associated with less-depressed visual fields among glaucoma patients and normal subjects. Visual fields were depressed by an average of 9 dB for glaucoma patients and 7 dB for normal subjects with high false-negative rates (greater than or equal to 33%), when compared with those with low false-negative rates. Apparent localized defects were observed among normal subjects with high false-negative rates. Most of these defects were located in the superior nasal and adjacent arcuate area.

Fixation, Ocular↗
PubMed1990

A randomized trial to improve compliance in urinary tract infection patients in the emergency department.

A randomized trial was used to evaluate two forms of a health belief model (HBM) intervention aimed at increasing compliance among 139 patients with urinary tract infections who presented to the emergency department. Patients who received an HBM clinical intervention administered in the ED, HBM telephone intervention two to four days after the ED visit, or both interventions were much more likely than control patients to both schedule and keep a follow-up referral appointment. Both the clinical and telephone interventions were designed to increase perceived susceptibility to complications of the urinary tract infection, seriousness of the complications, and benefits and costs of action. Other factors predicting compliance include age of the patient, urgency of the urinary tract infection as rated subjectively by the emergency physician, need for child care, whether transportation was available, and questioning the nurse about the referral appointment.

Acute Disease↗
PubMed1990

Bacterial colonization of the parotid duct in xerostomia.

Salivary flow rate and bacterial colonization of the parotid main duct were investigated in 17 patients referred for sialography and in 10 healthy controls. Cultures in the controls were negative whilst the patient group revealed bacterial colonization of the main duct, especially in those with the lowest flow rates. The implications of this finding in patients at high risk of endocarditis who will be undergoing sialography are discussed.

Adolescent↗
PubMed1990

The influence of halothane, isoflurane, and pentobarbital on cerebral plasma volume in hypocapnic and normocapnic rats.

Cerebral blood volume (CBV = cerebral plasma volume [CPV] + cerebral red cell volume [CRBCV]) is one determinant of intracranial pressure. In an effort to quantitate the effects of anesthetics and PaCO2 on CBV, the authors measured cerebral plasma volume (CPV) in normocapnic (PaCO2 approximately 42 mmHg) and hypocapnic (PaCO2 approximately 22 mmHg) rats receiving 1 MAC doses of isoflurane or halothane, or given an approximately equivalent dose of pentobarbital. All animals were paralyzed, their lungs mechanically ventilated, and body temperature kept normal throughout the study. CPV was measured using 14C-labeled dextran, a large (70,000 molecular weight [M.W.]), nondiffusible compound that was given intravenously and allowed to circulate for approximately 5 min. The experiments then were terminated by freezing the brains in situ with liquid N2 poured into a funnel affixed to the exposed calvarium. Isotope concentrations in solubilized brain and in plasma were determined by scintillation counting, and CPV was calculated as the ratio between these values. CPV during both hypocapnic and normocapnic pentobarbital anesthesia was less than with either volatile agent. During normocapnia, CPV for pentobarbital = 2.1 +/- 0.26 ml/100 g (mean +/- SD, n = 8), compared with 2.96 +/- 0.44 ml/100 g (n = 9) and 3.06 +/- 0.44 ml/100 g (n = 9) for halothane and isoflurane, respectively. There were no differences in CPV between the two volatile agents during normocapnia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Characterization of rat T helper cell clones specific for Bacteroides gingivalis antigen.

During the past several years, much interest has been directed towards delineating and characterizing different subsets of T helper (Th) cells in order to understand their roles in immune processes. In this study, we report the generation of antigen-specific rat Th cell clones and their characterization in terms of phenotype, function, and lymphokine production. The clones were derived by culturing purified splenic T cells from rats immunized with the pathogen Bacteroides gingivalis with equivalent numbers of irradiated spleen cells from nonimmune rats and B. gingivalis whole-cell antigen. The clones required antigen stimulation but not exogenously added interleukin-2 for growth and were maintained in culture for approximately 6 months. The cloned T cells proliferated in response to the mitogen concanavalin A and to B. gingivalis whole-cell antigen but not to other microbial antigens. Phenotypic characterization of the cloned T cells for cell surface markers demonstrated that these cells were OX19+ W3/25+ OX8- OX22- and therefore probably represented a mature subpopulation of CD4+ Th cells. These cloned T cells were positive for interleukin-2 receptor expression. Culture supernatants from the Th cell clones which were collected at various times after antigen stimulation exhibited low interleukin-2 activity and high gamma interferon activity. This in vitro study provides evidence of a rat Th cell subset that could represent an important population in regulating immune responses to microbial antigens.

Animals↗
PubMed1990

Glucose metabolism and recycling by hepatocytes of OB/OB and ob/ob mice.

Hepatocytes were prepared from livers of ob/ob (obese diabetic) mice and their lean (OB/OB) siblings that had been fasted for 24 h. The hepatocytes were incubated with [U-14C, 2-3H]-, [U-14C, 3-3H]-, and [U-14C, 6-3H]glucose at concentrations from 20 to 120 mM. 14C was recovered mainly in CO2, glycogen, and lactate. Tritium was recovered in water and glycogen. The yield in labeled products from [2-3H]glucose ranged from two to three times that from [U-14C]glucose. The yields from [3-3H]- and [6-3H]glucose were similar, and 1.3-1.7 times that from [U-14C]glucose. At 40 mM, total utilization of glucose by obese mice was about twice that for lean mice, but there was little difference at 120 mM. The rate of recycling between glucose and glucose 6-phosphate was calculated. An equation to calculate the rate of recycling of glucose from the 2-3H/U-14C ratio in glycogen is derived in the APPENDIX. Our results show that 1) the utilization of glucose by hepatocytes from obese diabetic mice exceeds that of their lean controls, 2) the rate of glucose phosphorylation in both groups greatly exceeds glucose uptake and the rate of glycogen synthesis, 3) glucose phosphorylation represents a difference between a high glucokinase rate and hydrolysis of glucose 6-phosphate, and 4) recycling of glucose carbon between glucose 6-phosphate and pyruvate occurs within mouse hepatocytes.

Animals↗
PubMed1990

Transplantation of adrenal medullary tissue to caudate nucleus using stereotactic techniques.

Stereotactic techniques were used to transplant adrenal medullary tissue to the head of the right caudate nucleus in 12 patients with Parkinson's disease. No significant lasting complications were seen. All patients had an initial improvement. 11 of the 12 patients remain improved over their preoperative condition after 6-18 months, 3 with good results and 9 with only modest improvement. At 6 months, the mean Schwab and England score had improved from 59.2 +/- 18.8 preoperatively to 75.8 +/- 15.1 (p less than or equal to 0.01) and the mean Hoehn and Yahr scale had improved from 3.42 +/- 0.90 to 2.92 +/- 0.63 (p less than or equal to 0.01).

Adrenal Medulla↗
PubMed1990

Regulation of antitrypsin and antichymotrypsin synthesis by MCF-7 breast cancer cell sublines.

We have examined the synthesis of the protease inhibitors alpha 1-antitrypsin (alpha 1-AT) and alpha 1-antichymotrypsin (alpha 1-ACHY) by variants of the MCF-7 human breast cancer cell line. Spent medium from MCF-7 203P cells, grown in the absence of serum, was found to contain immunoreactive alpha 1-AT and alpha 1-ACHY by Western blotting. In the presence of 10(-8) M estradiol, levels of both inhibitors were increased 3- to 6-fold. Incubation of spent medium with [125I]trypsin or [125I]chymotrypsin resulted in the formation of stable 75- and 90-kDa complexes identical to the complexes formed between these proteases and the protease inhibitors in plasma, showing the release of active protease inhibitors by MCF-7 cells in culture. Immunoprecipitation of 35S-labeled proteins from the medium of cells grown in the presence of [35S]methionine yielded comparable results, confirming hormonally sensitive synthesis of both protease inhibitors. Northern blot analysis suggests that stimulation of estradiol occurs at the level of transcription. Tetradecanoyl phorbol acetate (50 ng/ml) also stimulated alpha 1-AT and alpha 1-ACHY synthesis 2- to 4-fold, suggesting the involvement of protein kinase-C. Comparison studies with MCF-7 cell sublines ML, BK, 203P, and 300P (a variant spontaneously appearing after 100 passages of 203P) show a wide variation in synthesis of alpha 1-AT and alpha 1-ACHY proteins; sublines 203P and 300P synthesize both inhibitors, the ML subline synthesizes detectable amounts only of alpha 1-ACHY, while no detectable synthesis of either inhibitor was seen in the BK subline. Similar results were obtained for protease inhibitor mRNA transcription by Northern blotting, although low levels of alpha 1-AT mRNA transcription by the ML subline and of alpha 1-AT and alpha 1-ACHY mRNA transcription by the BK subline could be detected.

Blotting, Western↗
PubMed1990

A standardized data collection tool.

To successfully integrate data collection into the staff's responsibilities, the process must be simple, concise, and easy to use. The data collection tool described in this article includes all the important information at a glance, permits easy comparison with projected and actual thresholds, and analysis of data with follow-up action. It reduces the volumes of paperwork required in many systems. Since the indicators are written on only one paper, there is a reduction in transcription time. Additionally, one paper that contains a sample of twenty should be adequate for a unit-based indicator. Use of this tool reduces the number of papers that must be handled by the QA coordinator as well. Finally, the tool is flexible enough to use in a variety of settings.

Data Collection↗
PubMed1989

Isolation of temperature-sensitive mutants of 16 S rRNA in Escherichia coli.

Temperature-sensitive mutants have been isolated following hydroxylamine mutagenesis of a plasmid containing Escherichia coli rRNA genes carrying selectable markers for spectinomycin resistance (U1192 in 16 S rRNA) and erythromycin resistance (G2058 in 23 S rRNA). These antibiotic resistance alleles, originally identified by Morgan and co-workers, enable us to follow expression of cloned rRNA genes in vivo. Recessive mutations causing the loss of expression of the cloned 16 S rRNA gene were identified by the loss of the ability of cells to survive on media containing spectinomycin. The mutations were localized by in vitro restriction fragment replacement followed by in vivo marker rescue and were identified by DNA sequence analysis. We report here seven single-base alterations in 16 S rRNA (A146, U153, A350, A359, A538, A1292 and U1293), five of which produce temperature-sensitive spectinomycin resistance and two that produce unconditional loss of resistance. In each case, loss of ribosomal function can be accounted for by disruption of base-pairing in the secondary structure of 16 S rRNA. For the temperature-sensitive mutants, there is a lag period of about two generations between a shift to the restrictive temperature and cessation of growth, implying that the structural defects cause impairment of ribosome assembly.

Ampicillin↗