PubMed Health⌕ Search

Biomedical subjects

H Katz

Publications and source records attributed to H Katz.

At least 19 recordsLinked to original sources
PubMed1992

Golgi-like staining of visual cortex cells obtained by extracellular biocytin application in vitro.

We report here the application of biocytin (a biotin-lysine complex) as an extracellular tracer in vitro. Biocytin was applied extracellularly, revealing Golgi-like staining of cells in the adult in vitro rat visual cortex. Micropipettes were filled with a solution of 2.3-2.6% biocytin dissolved in 0.05 M Tris buffer, pH 7.4. Biocytin was applied by one of 3 methods: diffusion, pressure injection or drop application. Cell bodies and dendrites around the application site and their efferent axonal processes were stained; dendritic spines were often visible. The injection sites varied in size from a single cell to a diameter of 400 microns. When applied in layer I-III, few filled cells were also seen in layers IV and V, outside the application site. The drop application (5-10 microliters) of biocytin resulted in filling of cells throughout the cortex. The combination of biocytin and the slice preparation was found to be very useful in revealing cell morphology and tracing interlaminar connections in the visual cortex. The advantages of this technique are its ease of application, the precise and restricted injection sites, and Golgi-like morphological detail.

Animals↗
PubMed1992

Identification of polymorphic simple sequence repeats in the genome of the zebrafish.

The zebrafish has drawn a great deal of attention as a developmental system because it offers the ability to combine excellent embryology and genetics. Here, we report that simple sequence repeats are abundant in the zebrafish genome and are highly polymorphic between two outbred lines, making them useful markers for the construction of a genetic map of this organism.

Animals↗
PubMed1992

A genetic map of the mouse suitable for typing intraspecific crosses.

We report the construction of a genetic linkage map of the mouse, consisting entirely of genetic markers that can be rapidly typed by polymerase chain reaction and that show a high degree of polymorphism among inbred laboratory strains. Specifically, the map contains 317 simple sequence length polymorphisms at an average spacing of 4.3 cM and is detectably linked to approximately 99% of the mouse genome. In typical crosses between inbred laboratory strains, about 50% of the markers are polymorphic, making it straightforward to follow inheritance in almost any cross.

Animals↗
PubMed1992

Use of [3-3H]glucose and [6-14C]glucose to measure glucose turnover and glucose metabolism in humans.

[3-3H]glucose is frequently used to measure glucose turnover in humans. If fructose 6-phosphate-fructose 1,6-diphosphate cycling (Fpc) is negligible in both liver and muscle, then [3-3H]- and [6-14C]glucose (corrected for Cori cycle activity) should provide equivalent measures of glucose turnover. In addition, if glycogenolysis is fully suppressed, then [14C]lactate specific activity should equal that of [6-14C]glucose from which it was derived, and oxidation of [6-14C]glucose, as measured by rate of generation of 14CO2, should equal total glucose oxidation (i.e., that derived from intra- and extracellular pools) as measured by indirect calorimetry. To address these questions, glucose turnover was measured simultaneously with [3-3H]- and [6-14C]glucose in the basal state and in presence of low (approximately 200 pM) and high (approximately 750 pM) insulin concentrations. Glucose turnover rates measured with [3-3H]- and [6-14C]glucose were equivalent at all insulin concentrations, indicating that Fpc had no detectable effect on measurement of glucose appearance. [14C]lactate specific activity was lower (P less than 0.01) than that of [6-14C]glucose in the basal state but not during either low- or high-dose insulin infusion, implying that all lactate was derived from extracellular glucose. On the other hand, glucose oxidation as measured by rate of generation of 14CO2 was lower (P less than 0.05) than glucose oxidation as measured by indirect calorimetry during both insulin infusions, implying either that suppression of glycogenolysis was not complete in all tissues or that one or both of these techniques do not accurately measure glucose oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

A research-based reconsideration of the psychoanalytic theory of dreaming.

We present a brief review of sleep research which, when combined with psychoanalytic experience, has led to the hypothesis that REM sleep and dreaming serve the function of adaptation by the process of integration of information. We then report the results of a study of dreams, based on this hypothesis. We studied dreams and their relation to waking mental activity and found a correlation between problems in manifest dreams and those in pre- and postsleep waking life. Dreams can be understood on the basis of problems that appear in them. We also found evidence for a relation between the solution of problems in dreams and the fate of those problems the next day. We discuss these findings in relation to some of the controversies about dreaming, and then present suggestions for future research.

Dreams↗
PubMed1991

Effects of pancreas transplantation on postprandial glucose metabolism.

BACKGROUND: Because a pancreas allograft is placed in the pelvis, pancreas transplantation abolishes the normal gradient between portal-vein and peripheral-vein insulin concentrations and causes systemic hyperinsulinemia. Whether pancreas transplantation restores carbohydrate metabolism to normal is not known. METHODS: We studied seven patients with insulin-dependent diabetes mellitus after pancreas-kidney transplantation, seven nondiabetic patients after kidney transplantation (to control for immunosuppression), and eight normal subjects. Measurements were made after an overnight fast and after ingestion of a mixed meal. RESULTS: Although plasma glucose concentrations did not differ in the two transplant groups, plasma insulin concentrations were significantly higher in the diabetic pancreas-kidney recipients than in the nondiabetic kidney recipients, both before the meal (mean +/- SE, 102 +/- 15 vs. 53 +/- 6 pmol per liter; P less than 0.05) and afterward (123 +/- 22 vs. 61 +/- 6 nmol per liter per six hours; P less than 0.05). Plasma C-peptide concentrations were the same in both groups, indicating that hyperinsulinemia was due to decreased insulin clearance rather than increased insulin secretion. Despite drainage of the venous effluent from the transplanted pancreas into the systemic circulation, the values for splanchnic clearance of ingested glucose, suppression of hepatic glucose release, incorporation of carbon dioxide into glucose, stimulation of glucose oxidation, glucose uptake, and forearm glucose clearance were all similar in the transplant groups and differed minimally from the values in the normal group. The similar rates of glucose uptake in the presence of higher systemic insulin concentrations indicated that the extrahepatic tissues of the diabetic pancreas-kidney recipients were insulin-resistant. CONCLUSIONS: Despite systemic delivery of insulin, pancreas-kidney transplantation in patients with diabetes results in carbohydrate metabolism similar to that in nondiabetic subjects receiving the same immunosuppressive agents after kidney transplantation.

Adult↗
PubMed1991

Effects of chronic systemic insulin delivery on insulin action in dogs.

The metabolic consequences of the prolonged systemic insulin delivery associated with human pancreas transplantation have not been precisely defined. To determine if systemic insulin delivery in the absence of immunosuppressive agents results in alterations in hepatic or extrahepatic insulin action, three groups of dogs were studied 2 months after either a sham operation or after their pancreatic venous drainage was severed and anastomosed to the inferior vena cava or portal vein (sham, peripheral and portal groups, respectively). The pattern of venous drainage was documented by measuring vena cava and portal insulin concentrations before and after glucose injection. Systemic insulin concentrations were higher (p less than 0.05) in the peripheral group than in the portal group both following a 14-h fast and after intravenous glucose. During a hyperinsulinaemic euglycaemic clamp (1 mU.kg-1.min-1), glucose utilization (measured using [6(3)H]glucose) was slightly lower (p = 0.07) in the peripheral than in the portal group. Hepatic glucose release was equal in all groups. Carbon dioxide incorporation into glucose (an estimate of gluconeogenesis) was higher in the portal than peripheral group in the fasted state but not during insulin infusion. Plasma concentrations and flux rates of fatty acids and amino acids did not differ between groups. We conclude that chronic systemic insulin delivery results in a) systemic but not portal hyperinsulinaemia, b) a minimal impairment in insulin-stimulated glucose uptake, without altering insulin-induced suppression of hepatic glucose release, and c) no effect on fatty acid or amino acid turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Residents on the phone.

Explore the source record for details and available documents.

Health Maintenance Organizations↗
PubMed1985

Sex roles, gender, and fear.

Male and female college students classified as masculine, feminine, androgynous, or undifferentiated on the Bem (1974) Sex Role Inventory (N = 199) were given the Wolpe (1969) Fear Inventory. Significant differences in average fear scores were seen between men and women and between the four sex-role categories, with sex role and gender contributing equally to the variability. The argument is raised here that excessive fearfulness or fearlessness might be as much a product of sex-role conditioning as a product of gender.

Fear↗
PubMed1985

Oxygen tension in human tumors: in vivo mapping using CT-guided probes.

The role of oxygen in tumor response to therapy has been studied for several decades. We describe a technique that allows in vivo measurement of oxygen in tumors using computed tomography to guide probes. In the evaluation of 16 tumors, oxygen tensions were found to be substantially lower than surrounding tissue and varied nonrandomly. This technique has allowed construction of detailed tumor oxygen level maps.

Adult↗
PubMed1985

Utilization and morbidity: random or tandem?

Earlier studies have shown that one in eight children persist in being high users of health care services over long periods of time and, conversely, about the same proportion of children are consistently low users. As these studies failed to discover reasons for these persistent deviations from average, this study explored three possible explanations: persistent morbidity, mental health problem, and familial patterns of use. Although all three phenomena were associated with both persistence of high utilization of services as well as an overall large number of visits, the number of types of morbidity was the most significant correlate of high use. Children who were constantly low users of services were much more likely to have only a few types of morbidity whereas children who were constantly high users were much more likely to experience a wide variety of types of problems. These findings suggest that an understanding of the demand for health services requires an understanding of the interrelationships of illnesses within individuals rather than a focus on particular illnesses or particular types of illnesses.

Acute Disease↗
PubMed1985

Coordination of the contractile activity of bile canaliculi. Evidence from spontaneous contractions in vitro.

Rat hepatocytes, when isolated and maintained in primary culture, are capable of producing forceful contractions of their bile canaliculi, with contractions occurring on a regular basis once every 5.5 minutes. To determine whether the contraction of one bile canaliculus affected the contraction of a neighboring canaliculus, cinephotomicrographic studies of pairs of contiguous canaliculi were undertaken. The activity of 10 pairs of contiguous canaliculi, and 10 pairs of noncontiguous canaliculi which served as a control group, was recorded for a period of 12.5 hours at the rate of 1 frame every 15 seconds. Using frame-by-frame analysis of this period of observation, we determined the time of contraction of each of the canaliculi in the pairs. Cross-correlations were obtained for the contraction times of each of the 10 pairs of contiguous canaliculi and 10 control pairs. A peak in activity was found, with that peak occurring five frames or 75 seconds from the midline, whereas the noncontiguous controls showed no correlation in contractile activity. This finding indicates that, when one bile canaliculus contracts, a neighboring canaliculus is likely to contract after an interval of 1.25 minutes. That there is coordination of contractile activity of bile canaliculi suggests that, within the intact liver lobule, ordered motility function of the bile canaliculi may facilitate bile flow.

Animals↗
PubMed1984

Morbidity in childhood--a longitudinal view.

We examined all the morbidity experienced in a six-year period by a total of 2591 children who were continuously enrolled in a prepaid medical plan. The children had received 19,291 diagnoses, each of which was assigned to one of 14 types of morbidity, and the frequency of each type was determined. Although the typical child had at least one problem in 5 of the 14 types of morbidity in the six-year period, over 20 per cent of children had at least 8 different types of problems during that time. Children with a greater variety of acute problems and more frequent acute problems were also more likely to have nonacute problems during the six-year period. Conversely, children with nonacute problems had more acute problems than other children. Our findings indicate that morbidity, like use of health services, occurred in clusters in this population of children. Therefore, an understanding of the cause and projected outcome of morbidity among children will be incomplete if the focus is only on specific diseases or specific types of illnesses.

Adolescent↗
PubMed1984

Preventive care and overall use of services. Are they related?

The relationship between the use of services of children constantly enrolled in a prepaid group practice medical plan for six years and the completeness of their preventive care were examined. Children who were consistently low users of services were more likely to be lacking one or more components of standard preventive care, particularly general health assessments in older children and vision, hearing, and tuberculosis screening in younger children. Teenage children who were low users were at some risk of not receiving their tetanus-diphtheria immunization on time. The relationship between low use of services and incomplete preventive care persisted after controlling for the severity of morbidity, although children with more severe morbidity were somewhat less likely to be missing preventive care. Health facilities and practitioners should pay special attention to assessing the need for standard preventive care in children who are infrequent users of services.

Adolescent↗
PubMed1982

Subcutaneous facial emphysema complicating dental anaesthesia.

A 20 year-old female developed swelling and protrusions of the tongue and marked facial swelling while under general anaesthesia for dental restoration and gigivectomy. The initial diagnosis was angioedema; however x-rays showed marked subcutaneous emphysema more extensive in the perimandibular area with a minimal amount in the neck. There was no evidence of pneumomediastinum or pneumothorax. The iatrogenic subcutaneous emphysema was felt to be due to air-driven dental equipment. Tracheal intubation was maintained for 21 hours to prevent airway obstruction. The patient was treated with oxygen and antibiotics. Subcutaneous emphysema may occur following root canal therapy, tooth extraction, periodontal surgery and operative dentistry, due to the use of air-driven dental equipment. It has the potential to cause obstruction.

Adult↗
PubMed1982

Episode-based efficiency comparisons for physicians and nurse practitioners.

Most previous studies comparing the efficiency of new health practitioners with that of physicians have used the visit as the basic unit of output. Several researchers have noted, though, that the episode is a conceptually superior output unit in several respects, although it is more complex to deal with methodologically. This study demonstrates the application of episode-based methods for comparing the efficiency of physicians with that of nurse practitioners. Data are drawn from the information system of the Columbia Medical Plan and from observations of provider time inputs. The analysis is confined to care episodes for otitis media and sore throat in the Department of Pediatrics. Results indicate that per episode costs with nurse practitioners as the initial provider are approximately 20 per cent below the costs of episodes in which physicians are the initial provider. Examination of a limited amount of data on patient-reported measures of effectiveness indicates that while nurse practitioners' care is less costly, it is not less effective. These findings are particularly interesting in light of recent doubts expressed about cost-savings from using new health practitioners, and particularly nurse practitioners, in group practice settings.

Ambulatory Care↗