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Biomedical subjects

M Katz

Publications and source records attributed to M Katz.

At least 145 records · Page 8Linked to original sources
PubMed1996

Vitamin B-12 deficiency after gastric surgery for obesity.

Low serum vitamin B-12 concentrations after gastric bypass (GB) surgery for obesity were observed in 11 of 28 patients without detectable impairment of crystalline vitamin B-12 absorption. This was observed in 2 of 19 patients with vertical banded gastroplasty (VBG). In contrast, protein-bound vitamin B-12 absorption was markedly impaired, as demonstrated in eight of these patients after GB (n = 7) and VBG (n = 1). Correction of this impaired absorption occurred when protein-bound vitamin B-12 was incubated with an enzyme mixture before consumption. Simultaneous ingestion of the enzyme mixture with protein-bound vitamin B-12 did not improve absorption of the vitamin. In a separate experiment, 10 patients with a normal result from the Schilling test failed to correct low serum vitamin B-12 concentrations with a quantity of oral crystalline vitamin B-12 equal to the recommended dietary allowance of 2 micrograms, taken twice daily for 3 mo. Serum total homocysteine values declined during this interval. An oral daily dose of 350 micrograms crystalline vitamin B-12 raised the average serum vitamin B-12 concentration to an amount greater than the lower reference limit. A dose > 350 micrograms/d was required to raise all patients' vitamin B-12 concentrations above this concentration rather than just above the population mean. We conclude that because concentrations of oral crystalline vitamin B-12 were required to normalize serum vitamin B-12 concentrations, that a mechanism other than formation of a vitamin B-12 intrinsic factor complex is responsible for crystalline vitamin B-12 absorption after GB for obesity.

Adult↗
PubMed1996

Statistical modelling reveals demography and time are the main contributing factors in global sperm count changes between 1938 and 1996.

Declining sperm count reports have caused enormous concern to both the scientific community and to society. We reproduced the linear regression analysis and the quadratic model analysis using the 50 year sperm count data published in Carlsen's report and found that neither model adequately described the data. The reported decline in sperm count could be due to observational bias and overinterpretation of linear regression. In fact only 36% of the total variability in sperm count was explained by the linear model and 42% by the quadratic model. The linear model was no longer valid when three new European reports on sperm counts were included in the analysis. The quadratic model, however, suggested an upward trend of sperm count after 1975 (R2 = 0.48, P < 0.0001). Factors other than the 'passage of time' may have contributed to the initial decline of sperm count. An immediate candidate was demography. Our analysis showed that sperm counts in USA were significantly higher in 1938-1956 compared with those in 1957-1974 and 1975-1988, but not in the European or Asian/African/South American countries. The variability of the USA sperm count (1938-1988) explained by the linear and quadratic models was found to be 71 and 70% respectively. The quadratic model importantly indicated that the sperm count in USA decreases asymptotically towards a limiting value and global sperm counts could be increasing since 1970. The non-uniform nature of the global sperm count change suggested that local variations in pollution, diet but not global warming were important determinants of reproductive health.

Demography↗
PubMed1996

Spontaneous hepatic hemorrhage associated with pregnancy. Treatment by hepatic arterial interruption.

OBJECTIVE: The authors determined the effectiveness of hepatic arterial interruption in treating patients with spontaneous hepatic hemorrhage associated with pregnancy. BACKGROUND DATA: This rare syndrome frequently is seen with eclampsia/preeclampsia and is associated with high maternal mortality. The recommended treatment has been the use of local hemostatic measures. METHODS: The authors reviewed their experience managing eight patients by hepatic arterial interruption. RESULTS: Operative hepatic artery ligation was the initial method of controlling hepatic hemorrhage in three patients. One patient recovered, a hepatic sequestrum developed in one, and one patient died. Three patients survived after hepatic arterial embolization, but a sequestrum developed in one. Two patients died when hepatic arterial interruption was used after failed local hemostatic measures. CONCLUSIONS: The authors believe that hepatic arterial interruption is the preferred treatment for spontaneous hepatic hemorrhage associated with pregnancy. If the diagnosis is made at the time of cesarean section delivery, operative hepatic arterial ligation is indicated. If the diagnosis is made postpartum, percutaneous angiographic embolization should be performed.

Adolescent↗
PubMed1996

Convergence demands by spectacle magnifiers.

A general equation, c delta = k1b + k2sF, for finding the binocular convergence demands by spectacle magnifiers to view images at any distance is presented. Factor k1 in the equation yields the accommodative demand to view the image; factor k2 determines the actual reduction in convergence demand provided by the vendors' incorporation of base-in prism. When magnifiers from virtual images at finite distances, such as at the least distance of distinct vision or 25 cm, the interpupiliary distance (b), the separation between the lenses and the eyes (d), and the distance between the optical centers of the lenses (s) are basic quantities, according to this equation. The fundamental datum that the vendors should specify is the distance (s) between the optical centers of the lenses, rather than base-in prism. The specification of base-in prism is unrellable when images are formed at finite distances and the frame PD is not equal to the distance IPD. When the image is formed at infinity, that is when the angular magnification M = F/4, the convergence demand by spectacle magnifiers only depends on the separation between the optical centers of the lenses and the lens power, that is, c delta = sF. It is independent of the interpupillary distance (b) and the separation between the lenses and the eyes (d). We also present an equation, to find the disparity of the accommodative/convergence relation caused by spectacle magnifiers. Knowing the demands on convergence and accommodation, the practitioner can probably evaluate the potential for successful adaptation to spectacle magnifiers from routine measurements of positive and negative relative convergence and accommodation.

Accommodation, Ocular↗
PubMed1996

Integrating public health information and surveillance systems.

The Centers for Disease Control and Prevention (CDC) recognizes sound public health information is the essential ingredient of all of its work and the key to effective public health decision making. A CDC/ATSDR committee reached a consensus that CDC needed to streamline and consolidate its public health surveillance and information systems into an integrated system. With integrated systems, a wide range of diverse individual information systems will continue to exist but these systems must be coordinated, interconnected, comparable, and easy to use. The "glue" that holds these systems together consists of (1) uniform data standards, (2) communications networks, and (3) policy-level agreements regarding data access, sharing, and reduction of data collection burdens. By putting the appropriate policy-making apparatus and resources in place, CDC believes the end result will be a streamlined process that meets the information needs of CDC and its partners with less confusion and frustration.

Humans↗
PubMed1996

Red blood cell permeability to thiol compounds following oxidative stress.

The permeability of red blood cells (RBCs) to thiol containing compounds, reduced glutathione (GSH) and N-acetyl cysteine (NAC), has been studied in control adult and neonatal cells and after oxidative stress. NAC penetrates the cell membrane easily while GSH hardly permeates. We measured their capacity to enhance intracellular non-protein thiols (NPSH), after inducing damage to the membrane by formation of defects. Diamide, phenazine methosulfate (PMS) and t-butyl hydroperoxide (BHP) were chosen as exogenous oxidants, each inducing damage by a different mechanism. Our data indicate that although neonatal cells are more sensitive to oxidative stress, only membrane damage induced by diamide, renders adult and neonatal cells permeable to GSH. NAC treatment enhances thiol levels in cells exposed to oxidizing agents, as well as in control cells.

Acetylcysteine↗
PubMed1996

Effect of ethanol on cholecystokinin-stimulated zymogen conversion in pancreatic acinar cells.

Exocrine pancreatic zymogens are proteolytically processed to active forms after they are secreted into the small intestine. However, intracellular conversion of zymogens to active forms can be stimulated by treating pancreatic acinar cells with high doses of cholecystokinin (0.1 microM) or carbamylcholine (0.1 mM). The high doses of cholecystokinin are unlikely to be achieved physiologically. The ability of ethanol to sensitize the acinar cell to zymogen conversion Induced by cholecystokinin or carbamylcholine was examined. Ethanol (10-200 mM) had no effect alone or when combined with carbamylcholine. However, ethanol (25 mM) added with low-dose cholecystokinin (0.1 nM) generated zymogen conversion that was 1) sixfold higher than cholecystokinin alone and 2) equivalent to that generated by highdose cholecystokinin (10 microM). The ability of ethanol to enhance cholecystokinin-induced zymogen conversion was dependent on the dose of ethanol and the duration of ethanol treatment. The cholecystokinin receptor antagonist, L-364,718, blocked the conversion stimulated by the addition of ethanol with cholecystokinin. This effect of ethanol did not change the affinity or number of cholecystokinin receptors, suggesting an effect more distal in the stimulus-activation cascade. These findings demonstrate that ethanol selectively sensitizes the pancreatic acinar cell to cholecystokinin-stimulated zymogen proteolysis.

Animals↗
PubMed1996

Correlational patterns of cerebral glucose metabolism in never-medicated schizophrenics.

We studied 18 never-mediated schizophrenic patients and 22 normal control subjects with 18F-deoxyglucose (FDG) positron emission tomography. Patients and controls performed the continuous performance test during FDG uptake. Cortical and subcortical structures comprising two circuits selected on the basis of several theoretical models of schizophrenia were examined. The correlation of glucose metabolic rate (GMR) for each structure in each circuit with connected structures was calculated and tested for two-tailed significance. Schizophrenics showed significantly different patterns of intercorrelations for both circuits. The largest difference was in the correlation of GMR in the anterior thalamus with the frontal cortex, a key element in the thalamo-cortical-striatal circuit suggested to be abnormal in some models of schizophrenia. Correlations of the frontal lobe with other regions were also more positive in normal controls than schizophrenics; controls had three correlational paths from the frontal cortex (to temporal cortex, ventral anterior thalamus, and dorsal medial thalamus) with significantly more positive correlations than schizophrenics perhaps consistent with other findings of frontal cortical dysfunction in schizophrenia. Normal controls also had both more significant positive and more significant negative correlations between the occipital cortex and other brain areas than schizophrenics. Correlations between homologous areas in the right and left hemispheres were prominent in both groups.

Adult↗
PubMed1996

Haemodialysis arteriovenous access--a prospective haemodynamic evaluation.

BACKGROUND: Factors affecting cardiac function in dialysis patients include arterial blood pressure, anaemia, intravascular volume, and the arteriovenous (a-v) access. Cardiac failure has been directly attributed to dialysis a-v access in several cases. The contribution of the a-v access to cardiac performance has been tested, in the past, by a short manual compression on the fistula, but this technique has obvious limitations. METHODS: The present study examined prospectively the effect of dialysis a-v access on both cardiac function and various hormonal responses. Ten patients (age, mean +/- SD, 59.6 +/- 12.3) with end-stage renal failure being prepared for chronic dialysis therapy were included. All patients underwent an echocardiographic study before and 2 weeks after the creation of the a-v access. Plasma atrial natriuretic peptide (ANP), plasma renin activity (PRA), and plasma aldosterone were measured at the same time periods. RESULTS: Following the creation of the a-v fistula or graft, shortening fraction increased by 15.8 +/- 6.3% (P < 0.01), stroke volume increased by 21.9 +/- 5.3% (P < 0.01), ejection fraction increased by 10.6 +/- 4.5% (P < 0.02), cardiac output increased by 19.0 +/- 6.9% (P < 0.02), and cardiac index increased by 18.3 +/- 7.1% (P = 0.05). Systemic vascular resistance decreased by 23.5 +/- 7.1% (P < 0.01). There was no change in blood pressure, heart rate, weight, haemoglobin or serum creatinine. ANP increased by 83.7 +/- 17.0% following the a-v access operation (P < 0.001), PRA decreased by 41.2 +/- 10.0% (P < 0.05), and plasma aldosterone did not change. None of the patients developed overt high-output cardiac failure. CONCLUSIONS: This study shows that at least in the short term following the creation of a dialysis a-v access, a mild state of volume overload develops, which is offset by the ¿unloading' effect of the decreased peripheral vascular resistance; the latter is probably mediated by secretion of ANP in response to atrial stretching.

Adult↗
PubMed1996

Torticollis: an unusual presentation of spontaneous pneumomediastinum.

Torticollis is a common clinical sign encountered by pediatricians in a wide variety of childhood illnesses including those from traumatic, neurologic, infectious, inflammatory, and psychogenic causes. We describe a case of spontaneous pneumomediastinum (SPM) manifested as acute torticollis. To the best of our knowledge, torticollis as a result of spontaneous pneumomediastinum has not yet been described. Pneumomediastinum should be included in the differential diagnosis of torticollis.

Acute Disease↗
PubMed1996

Plasma fibrinogen in Israeli Moslem and Jewish school-children: distribution and relation to other cardiovascular risk factors. The Petah Tikva project.

Plasma fibrinogen levels were measured in 1,175 Israeli schoolchildren, aged 9-18 years, originating from diverse ethnic groups. The Moslem children displayed striking differences in levels and age-patterns of fibrinogen compared to Jewish children. Lower mean plasma fibrinogen levels in boys aged 9-10, 13-14 and 16-18 were observed among Moslem boys, compared to their Jewish counterparts born in Israel. Moslem girls showed lower levels of fibrinogen than Jewish Israeli girls at ages 9-10 and 16-18. While the Jewish children displayed an age-associated fibrinogen pattern comparable at the three age groups, the levels for Moslem children increased pre-puberty and decreased post-puberty, peaking at 13-14 years. No significant difference in mean plasma fibrinogen was found between sexes within ethnic groups. A number of statistically significant but low correlations (-0.32 to 0.24) were found between plasma fibrinogen and high density lipoprotein cholesterol (HDL-C) as a percentage of total cholesterol, triglycerides, blood glucose, uric acid, blood pressure, Quetelet index and sports activity. The difference between fibrinogen levels might point to a possible ethnicity risk factor explanation rather than environmentally acquired factors.

Adolescent↗
PubMed1995

Serotonin-stimulated intracellular calcium mobilization in platelets from alcoholic men.

Numerous lines of evidence have suggested a key role for serotonin (5-hydroxytryptamine, 5HT) pathways in the regulation of alcohol consumption. To explore the functioning of the 5HT2 receptor in alcoholism, 5HT-stimulated intracellular calcium response was measured in platelets from abstinent alcoholic patients and normal comparison subjects. No difference in resting or stimulated calcium levels was observed. This finding suggests that 5HT2 receptor function is unaffected in non-drinking alcoholic subjects. The previously reported 5HT inhibition in actively drinking alcoholic subjects is likely to be a state rather than trait marker of alcoholism.

Adult↗
PubMed1995

Differences in cord serum retinol concentrations by ethnic origin in the Negev (southern Israel).

Subclinical vitamin A deficiency is related to increased morbidity and mortality in infants and children. Previous studies indicate that the traditional diet of Moslem Bedouins, an important ethnic group in Southern Israel, is low in vitamin A content. Cord serum retinol (vitamin A) concentration was measured by HPLC in samples from 251 apparently healthy (birth weight > 2500 g, gestational age > 37 weeks) neonates with no abnormal perinatal events, 138 Jews and 113 Bedouins. Retinol < 15 micrograms/dl was measured in a total of 14% of infants: in 7% of Jewish and 26% of Bedouin newborns (P < 0.001). However, mean cord serum retinol was only slightly lower in Bedouins than in Jews (30 +/- 26 vs. 37 +/- 27 micrograms/dl mean +/- S.D., n.s.). Cord serum retinol was not related to socioeconomic indices. Cord serum retinol < 15 micrograms/dl was measured in 25% and in 12% of infants with birth weight less than and equal or greater than 3000 g, respectively (P = 0.01), and in 28% and 13% of infants with gestational age 37-38 weeks and 39-41 weeks, respectively (P = 0.03). Low cord serum retinol was found to be prevalent in Southern Israel, particularly in Bedouin infants. In the population of healthy neonates studied, very low cord serum retinol concentrations were found more frequently in infants born with a lower weight and/or after a shorter gestation.

Arabs↗
PubMed1995

Arterial anatomic considerations in colon interposition for esophageal replacement.

BACKGROUND: Little has been written regarding the arterial anatomy predictive of success following esophagectomy and colon interposition. DESIGN: Retrospective review. SETTING: University teaching hospital. PATIENTS: Twenty-five patients undergoing planned left colon interposition. INTERVENTION: Colon interposition was performed via an isoperistaltic left colon graft based on the ascending branch of the left colic artery. MAIN OUTCOME MEASURES: Five angiographic features were considered important to successful use of the left colon: (1) a patient inferior mesenteric artery, (2) a visible ascending branch of the left colic artery, (3) a well-defined anastomosis between the middle colic and left colic systems, (4) a single middle colic trunk prior to its division into right and left branches, and (5) a separate origin of the right colic artery. Venous drainage via a patent marginal vein, inferior mesenteric vein, and superior hemorrhoidal veins was preserved in all patients. RESULTS: Left colon interposition could be performed in 21 (84%) of 25 patients. Eighty percent of the patients (20/25) had at least four of the five criteria thought necessary for optimal graft perfusion. Three or fewer criteria were present in five patients, three of whom underwent gastric interposition. The inferior mesenteric artery was patent in all patients except one who required a right colon interposition. Ninety-two percent (23/25) demonstrated an adequate ascending left colic artery. The superior-inferior mesenteric artery anastomosis was seen in 52% (13/25). A single-trunked middle colic artery was present 80% (20/25) of the time. A single incidence of graft necrosis occurred secondary to venous insufficiency. Ninety-six percent of patients (24/25) were able to swallow without difficulty at the time of discharge from the hospital. CONCLUSIONS: Replacement of the esophagus with colon can be successful in over 80% of patients screened by angiographic criteria. Patients with an occluded or stenotic inferior mesenteric artery or variant middle colic arterial anatomy should undergo an alternate reconstruction.

Anastomosis, Surgical↗
PubMed1995

Plain radiography for diagnosis of gastrointestinal perforation in immune-compromised children--is it enough?

Gastrointestinal perforation is a surgical emergency in the pediatric patient and any delay in diagnosis might be hazardous. In immunocompromised children, the clinical signs of perforation may be blunted. We describe a child with acute lymphoblastic leukemia (ALL) and a perforated appendix and ileum in whom computerized tomography (CT) revealed extraluminal air that was not initially identified on plain abdominal film. Our case demonstrates the importance of early abdominal CT and ultrasound examination in detecting these potentially lethal complications.

Acute Disease↗