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Biomedical subjects

J Katz

Publications and source records attributed to J Katz.

At least 361 records · Page 20Linked to original sources
PubMed1992

Direct quantitation of right and left ventricular volumes with nuclear magnetic resonance imaging in patients with primary pulmonary hypertension.

To test the utility of electrocardiographically gated spin echo nuclear magnetic resonance (NMR) imaging in quantitating right and left ventricular volumes and function in patients with primary pulmonary hypertension, right and left ventricular end-diastolic and end-systolic volumes, stroke volumes and ejection fractions were determined in 11 patients with primary pulmonary hypertension and in 10 subjects with normal echocardiographic findings. Ventricular chamber volumes were computed by summing the ventricular chamber volumes of each NMR slice at end-diastole and end-systole. This technique was verified by comparison of results obtained by this method and with the water displacement volumes of eight water-filled latex balloons and ventricular casts of eight excised bovine hearts. In the patients with primary pulmonary hypertension, right ventricular volume indexes were 121 +/- 45 ml/m2 at end-diastole and 70.1 +/- 41.6 ml/m2 at end-systole; both values were significantly greater than values in the normal subjects (67.9 +/- 13.4 and 27.9 +/- 7.5 ml/m2, respectively). Left ventricular end-diastolic volume index was significantly less in the patients (44.9 +/- 9.7 ml/m2) than in the normal subjects (68.9 +/- 13.1 ml/m2). There was no significant difference in left ventricular end-systolic volume between the two groups (24.4 +/- 8.6 and 27.1 +/- 7.8 ml/m2, respectively). Right and left ventricular ejection fractions in the patients with primary pulmonary hypertension (0.43 +/- 0.21 and 0.46 +/- 0.15, respectively) were significantly less than values in normal subjects (0.59 +/- 0.09 and 0.6 +/- 0.11, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Seeking consensus on important aspects of nursing care.

The authors suggest that the lack of consensus among nurses about important indicators and other measures of quality stems from the lack of consensus on important aspects of nursing care. This article reports on a national conference for nursing quality assurance in which 176 nurses representing 11 specialties developed lists of universal and specialty practice important aspects of care. It discusses questions raised at the conference about definitions of terms, as well as plans for additional follow-up work.

Consensus Statements as Topic↗
PubMed1992

An evaluation of optic disc and nerve fiber layer examinations in monitoring progression of early glaucoma damage.

From annual examinations of 813 ocular hypertensive eyes, the authors compared optic disc and nerve fiber layer photographs in 2 age-matched subgroups: 37 eyes that converted to abnormal visual field tests at the end of a 5-year period and 37 control eyes that retained normal field tests. Disc change was detected in only 7 of 37 (19%) converters to field loss and in 1 of 37 (3%) controls. Progressive nerve fiber layer atrophy was observed in 18 of 37 (49%) converters and in 3 of 37 (8%) controls. Serial nerve fiber layer examination was more sensitive than color disc evaluation in the detection of progressive glaucoma damage at this early stage of glaucoma. The evaluation of cup-to-disc ratio or of the nerve fiber layer appearance in the initial photograph taken 5 years before field loss were equally predictive of future field damage. The position of nerve fiber layer defects was highly correlated with the location of subsequent visual field loss.

Aged↗
PubMed1992

The use of the CO 2 laser in oral surgery in the military.

From 1987 to 1990, there were 122 soldiers treated with the CO 2 laser (Sharplan 1010) in the Laser Center of the Israel Defense Forces. A variety of benign oral lesions, vascular tumors, and other oral lesions were excised or vaporized. Twenty-four soldiers with impacted wisdom teeth and wide pericoronitis underwent operculectomy using the CO 2 laser. The CO 2 laser has the ability to perform accurate hemostasis surgery, with minimal postoperative pain and edema, and rapid healing, resulting in fast recovery without significant discomfort. These advantages are particularly important in the military since soldiers can return to their duties immediately after surgery.

Adolescent↗
PubMed1992

Impact of vitamin A supplementation on the incidence of infection in elderly nursing-home residents: a randomized controlled trial.

The aim of this study was to determine if vitamin A supplementation reduces the incidence of bacterial infections among elderly nursing-home residents. One hundred and nine patients were enrolled into a double-masked, placebo-controlled trial at an academically affiliated nursing home. Fifty-six patients received a single capsule containing 1,000 IU of vitamin A (placebo) and 53 received a single capsule containing 200,000 IU of vitamin A. Antibiotic-treated infections were enumerated for 90 days after dosing and infection rates were expressed per 1000 days of follow-up. There were 42 antibiotic-treated infections altogether, 21 in each group. The infection rates in the vitamin A and placebo groups were 4.7 and 4.3 per 1,000 days of follow-up, respectively (relative risk 1.1; 95% CI 0.6, 2.0). The findings of this study do not support a role for vitamin A supplements for the prevention of infections among frail elderly nursing-home patients.

Aged↗
PubMed1992

Xerophthalmia and growth in preschool Indonesian children.

Approximately 4000 preschool children in West Java, Indonesia, were examined for xerophthalmia and weighed and measured at 3-mo intervals from March 1977 to December 1978. Children recovering from xerophthalmia over a 3-mo interval gained an average of 124 g (95% CI 42-206) more over 3 mo than normal children. Their height gain was similar to normal children's. Children who developed xerophthalmia during a 3-mo period gained 199 g (95% CI 114-313) less and grew 0.28 cm (95% CI 0.12, 0.44) less than their normal peers. Children with chronic xerophthalmia gained 120 g (95% CI 49-191) less and grew 0.21 cm (95% CI 0.05-0.37) less than normal children. These data suggest that linear and ponderal growth is adversely affected by chronic and incident xerophthalmia, but that catch-up ponderal growth is experienced by children recovering from xerophthalmia.

Body Height↗
PubMed1992

Preemptive analgesia. Clinical evidence of neuroplasticity contributing to postoperative pain.

Recent evidence suggests that surgical incision and other noxious perioperative events may induce prolonged changes in central neural function that later contribute to postoperative pain. The present study tested the hypothesis that patients receiving epidural fentanyl before incision would have less pain and need fewer analgesics post-operatively than patients receiving the same dose of epidural fentanyl after incision. Thirty patients (ASA physical status 2) scheduled for elective thoracic surgery through a posterolateral thoracotomy incision were randomized to one of two groups of equal size and prospectively studied in a double-blind manner. Epidural catheters were placed via the L2-L3 or L3-L4 interspaces preoperatively, and the position was confirmed with lidocaine. Group 1 received epidural fentanyl (4 micrograms/kg, in 20 ml normal saline) before surgical incision, followed by epidural normal saline (20 ml) infused 15 min after incision. Group 2 received epidural normal saline (20 ml) before surgical incision, followed by epidural fentanyl (4 micrograms/kg, in 20 ml normal saline) infused 15 min after incision. No additional analgesics were used before or during the operation. Anesthesia was induced with thiopental (3-5 mg/kg) and maintained with N2O/O2 and isoflurane. Paralysis was achieved with pancuronium (0.1 mg/kg). Postoperative analgesia consisted of patient-controlled intravenous morphine. Visual analogue scale pain scores were significantly less in group 1 (2.6 +/- 0.44) than in group 2 (4.7 +/- 0.58) 6 h after surgery (P less than 0.05), by which time plasma fentanyl concentrations had decreased to subtherapeutic levels (less than 0.15 ng/ml) in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia, Epidural↗
PubMed1992

A randomized, double-blind comparison of lumbar epidural and intravenous fentanyl infusions for postthoracotomy pain relief. Analgesic, pharmacokinetic, and respiratory effects.

Although epidural opioids frequently are used to provide postoperative analgesia, several articles have suggested that the analgesia after epidural fentanyl is similar to that after an equal dose of fentanyl given intravenously. To address this issue further, 29 postthoracotomy patients were studied in a randomized, double-blinded trial comparing a lumbar epidural fentanyl infusion with an intravenous fentanyl infusion for analgesia, plasma fentanyl pharmacokinetics, and respiratory effects for 20 h postoperatively. In all patients in both groups, good analgesia was achieved (pain score less than 3, maximum 10) over a similar time course, although the patients receiving epidural infusion required a significantly larger fentanyl infusion dose than did the patients receiving intravenous infusion (group receiving epidural fentanyl infusion: 1.95 +/- 0.45 micrograms.kg-1.h-1; group receiving intravenous fentanyl infusion: 1.56 +/- 0.36 micrograms.kg-1.h-1; P = 0.0002). The time course for the plasma fentanyl concentrations was similar in the two groups, and plasma fentanyl concentrations were not significantly different at any sampling period (T7-T20; group receiving epidural fentanyl infusion: 1.8 +/- 0.5 ng/ml; group receiving intravenous fentanyl infusion: 1.6 +/- 0.6 ng/ml; P = 0.06). Similarly, calculated clearance values for the two groups were not significantly different (group receiving epidural fentanyl infusion: 0.95 +/- 0.26 l.kg-1.h-1; group receiving intravenous fentanyl infusion: 0.87 +/- 0.25 l.kg-1.h-1; P = 0.3). Both groups demonstrated a similar degree of mild to moderate respiratory depression postoperatively, which was assessed with continuous respiratory inductance plethysmography and sequential arterial blood gas analysis. Side effects (nausea, vomiting, pruritus) were mild and did not differ between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Protective effect of oral acetylcysteine against the hepatorenal toxicity of carbon tetrachloride potentiated by ethyl alcohol.

Considering the well-documented protection of acetylcysteine (AC) in hepatotoxicity related to acetaminophen, we studied the preventive potential of AC against mild hepatotoxicity of CCl4, potentiated with ethyl alcohol (ETH) and the role of tissue glutathione. Rats fed a liquid diet with 30% of energy from ETH, had-intraperitoneal CCl4 administered in three injections, at 7-day intervals. AC was ingested at the level for acetaminophen overdose. ETH markedly potentiated the injury induced by CCl4, as evidenced by higher values of serum alanine aminotransferase (ALT), urinary bile acids (BA), serum creatinine, histological score of liver cell necrosis, mortality and by lower body weights and lower liver glutathione, when compared with CCl4 alone. Protective effect of AC consisted of a lesser hepatocytic necrosis, better body weights and higher liver glutathione. We conclude, that AC favorably modifies liver damage induced by CCl4 and potentiated with ETH. There is a preventive role for AC in subjects who combine ETH overuse with exposure to hepatotoxic xenobiotics, whose toxicity is modified by tissue glutathione.

Acetylcysteine↗
PubMed1992

Oral changes in interleukin-2 treated patients: a preliminary report.

Immunotherapy with high doses of interleukin-2 (IL-2) in patients with metastatic cancer is accompanied by multiorgan side effects. To determine the effect of this treatment on oral tissues, 5 cancer patients receiving a course of recombinant IL-2 (rIL-2) were followed. Oral pathology and subjective oral complaints were noted. Whole saliva parameters and routine blood and urine values were recorded daily before, during and after treatment. Mucositis and diminution of salivary flow occurred in all patients. Concomitantly, salivary sodium and protein were elevated.

Adult↗
PubMed1992

Humoral response to Porphyromonas (Bacteroides) gingivalis in rats: time course and T-cell dependence.

In this study, we describe the time course and T-cell dependence of the serum antibody response to the periodontopathogen Porphyromonas (Bacteroides) gingivalis in an experimental rat model. Normal Fischer rats were challenged by a local injection of P. gingivalis (2 x 10(8) bacteria) into gingival tissue or by the administration of a similar number of bacteria by the intravenous (i.v.) route on days 0, 2, and 4. Serum antibody activity was detected within 1 week and peaked at 8 weeks after gingival challenge. A similar but lower response was seen for rats challenged by the i.v. route. The response in both groups of rats was mainly of the immunoglobulin G (IgG) isotype; some IgM but no IgA antibody activity was detected. Analysis of the IgG subclass revealed mainly IgG2c in animals challenged locally in the gingiva with P. gingivalis, whereas IgG2b predominated in rats challenged by the i.v. route. The importance of T cells in the response was established by demonstrating the absence of serum IgG antibodies in nude rats after a local challenge of gingival tissue with P. gingivalis. Nude rats given purified splenic T cells from normal rats immunized systemically with P. gingivalis prior to a local gingival challenge showed a rapid appearance of serum antibody activity that peaked between 4 and 6 weeks. This initial peak occurred 2 to 4 weeks earlier than that seen in normal animals. Fluorescence-activated cell sorter analysis of splenic lymphoid cells from these nude rats revealed a helper T-cell population. The levels of serum IgG antibodies in nude rats given nonimmune T cells rose slowly, and the antibodies were mainly of the IgG2a and IgG2b subclasses. Nude rats given immune T cells showed a rapid increase primarily in IgG2b antibody levels following a local gingival challenge. These findings suggest that the immune helper T-cells contributed to the rapid development of the response to P. gingivalis. Furthermore, it is likely that the IgG subclass response to P. gingivalis in these nude rats was related to the splenic origin of the T cells used for adoptive transfer.

Animals↗
PubMed1992

Evolution of the H3 influenza virus hemagglutinin from human and nonhuman hosts.

The nucleotide and amino acid sequences of 40 influenza virus hemagglutinin genes of the H3 serotype from mammalian and avian species and 9 genes of the H4 serotype were compared, and their evolutionary relationships were evaluated. From these relationships, the differences in the mutational characteristics of the viral hemagglutinin in different hosts were examined and the RNA sequence changes that occurred during the generation of the progenitor of the 1968 human pandemic strain were examined. Three major lineages were defined: one containing only equine virus isolates; one containing only avian virus isolates; and one containing avian, swine, and human virus isolates. The human pandemic strain of 1968 was derived from an avian virus most similar to those isolated from ducks in Asia, and the transfer of this virus to humans probably occurred in 1965. Since then, the human viruses have diverged from this progenitor, with the accumulation of approximately 7.9 nucleotide and 3.4 amino acid substitutions per year. Reconstruction of the sequence of the hypothetical ancestral strain at the avian-human transition indicated that only 6 amino acids in the mature hemagglutinin molecule were changed during the transition between an avian virus strain and a human pandemic strain. All of these changes are located in regions of the molecule known to affect receptor binding and antigenicity. Unlike the human H3 influenza virus strains, the equine virus isolates have no close relatives in other species and appear to have diverged from the avian viruses much earlier than did the human virus strains. Mutations were estimated to have accumulated in the equine virus lineage at approximately 3.1 nucleotides and 0.8 amino acids per year. Four swine virus isolates in the analysis each appeared to have been introduced into pigs independently, with two derived from human viruses and two from avian viruses. A comparison of the coding and noncoding mutations in the mammalian and avian lineages showed a significantly lower ratio of coding to total nucleotide changes in the avian viruses. Additionally, the avian virus lineages of both the H3 and H4 serotypes, but not the mammalian virus lineages, showed significantly greater conservation of amino acid sequence in the internal branches of the phylogenetic tree than in the terminal branches. The small number of amino acid differences between the avian viruses and the progenitor of the 1968 pandemic strain and the great phenotypic stability of the avian viruses suggest that strains similar to the progenitor strain will continue to circulate in birds and will be available for reintroduction into humans.

Amino Acid Sequence↗
PubMed1992

Psychophysical correlates of phantom limb experience.

Phantom limb phenomena were correlated with psychophysiological measures of peripheral sympathetic nervous system activity measured at the amputation stump and contralateral limb. Amputees were assigned to one of three groups depending on whether they reported phantom limb pain, non-painful phantom limb sensations, or no phantom limb at all. Skin conductance and skin temperature were recorded continuously during two 30 minute sessions while subjects continuously monitored and rated the intensity of any phantom limb sensation or pain they experienced. The results from both sessions showed that mean skin temperature was significantly lower at the stump than the contralateral limb in the groups with phantom limb pain and non-painful phantom limb sensations, but not among subjects with no phantom limb at all. In addition, stump skin conductance responses correlated significantly with the intensity of non-painful phantom limb paresthesiae but not other qualities of sensation or pain. Between-limb measures of pressure sensitivity were not significantly different in any group. The results suggest that the presence of a phantom limb, whether painful or painless, is related to the sympathetic-efferent outflow of cutaneous vasoconstrictor fibres in the stump and stump neuromas. The hypothesis of a sympathetic-efferent somatic-afferent mechanism involving both sudomotor and vasoconstrictor fibres is proposed to explain the relationship between stump skin conductance responses and non-painful phantom limb paresthesiae. It is suggested that increases in the intensity of phantom limb paresthesiae follow bursts of sympathetic activity due to neurotransmitter release onto apposing sprouts of large diameter primary afferents located in stump neuromas, and decreases correspond to periods of relative sympathetic inactivity. The results of the study agree with recent suggestions that phantom limb pain is not a unitary syndrome, but a symptom class with each class subserved by different aetiological mechanisms.

Adult↗
PubMed1992

On the determination of turnover in vivo with tracers.

Theoretical and practical aspects of the application of tracer methods for the measurement of turnover of blood-borne compounds are discussed, with special regard to lactate. The validity of the application of the tracer into the aortic arch and sampling from the right atrium (A-V), the administration of tracer into the vena cava and sampling from the aorta (V-A), and sampling to the determination of turnover are examined, using numerical examples. It is shown that the difference between specific activity in arterial and mixed venous blood depends mainly on the cardiac output, the ratio of tracee turnover to the mass of circulating tracee, and the sites of production and utilization of the tracee. Conditions are shown under which the A-V and V-A modes overestimate or underestimate the true rate of turnover. In theory, the A-V mode provides an exact estimate of turnover when the mean specific activity of the tracee in the whole body equals the specific activity of mixed venous blood in the right heart. It is shown that, for compounds with a high turnover rate, the underestimate in the A-V mode is small, and the mode provides a close approximation of true turnover. The underestimate in the V-A mode at high turnover rates is extensive. Experimental evidence indicates that, in several animal species, the specific activity of lactate and several amino acids in several organs and tissues nearly equals that in the venous blood, with the A-V mode providing a close approximation of the true turnover for these compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

Psychophysiological contributions to phantom limbs.

Recent studies of amputees reveal a remarkable diversity in the qualities of experiences that define the phantom limb, whether painless or painful. This paper selectively reviews evidence of peripheral, central and psychological processes that trigger or modulate a variety of phantom limb experiences. The data show that pain experienced prior to amputation may persist in the form of a somatosensory memory in the phantom limb. It is suggested that the length and size of the phantom limb may be a perceptual marker of the extent to which sensory input from the amputation stump have re-occupied deprived cortical regions originally subserving the amputated limb. A peripheral mechanism involving a sympathetic-efferent somatic-afferent cycle is presented to explain fluctuations in the intensity of paresthesias referred to the phantom limb. While phantom pain and other sensations are frequently triggered by thoughts and feelings, there is no evidence that the painful or painless phantom limb is a symptom of a psychological disorder. It is concluded that the experience of a phantom limb is determined by a complex interaction of inputs from the periphery and widespread regions of the brain subserving sensory, cognitive, and emotional processes.

Amputation, Surgical↗
PubMed1992

Transfer and metabolism of retinol by the perfused human placenta.

The transfer and metabolism of retinol by human placenta was investigated using an in vitro perfusion system with independent maternal and fetal circulations. 3H-retinol bound to albumin added to the maternal perfusate was rapidly taken up and concentrated by the placenta to levels 16.5 +/- 5.28 times the maternal perfusate. Approximately 8% of the retinol retained in the placenta was esterified. No metabolites were detected in the perfusates. Perfusion of placenta with retinol bound to retinol-binding protein (RBP) reduced the placental concentration to 4.4 +/- 1.72 times the maternal concentration and eliminated evidence of metabolism. The transfer rate of RBP:3H-retinol was less than that of albumin:14C-retinol when measured concurrently in three experiments (clearances 0.11 versus 0.75 mL/min, 0.21 versus 1.7 mL/min, and 0.29 versus 0.48 mL/min, respectively). Transfer of the radioactive retinol was more rapid than 125I-RBP or albumin, indicating that retinol was transferred independently of the proteins. The transfer index of retinol (clearance retinol:clearance L-glucose) was 0.73 +/- 0.085 compared to 2.1 +/- 0.36 for thiamin and 3.4 +/- 0.95 for riboflavin, both water-soluble vitamins with active transport systems. The retinol transferred to the fetal perfusate is not bound to RBP, as demonstrated by gel filtration chromatography and chromatography on a transthyretin affinity column, despite the availability of RBP in the cord serum added to the perfusate. The endogenous retinol in the cord serum is bound to RBP.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport, Active↗