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Biomedical subjects

M Katz

Publications and source records attributed to M Katz.

At least 289 records · Page 16Linked to original sources
PubMed1988

An instrument for measuring the modulation transfer functions of low power telescopes and telemicroscopes.

An instrument using an electro-optical Fourier method for measuring the modulation transfer function (MTF) of low power telescopes and telemicroscopes is described. Because these devices are afocal, or nearly so, relay optics are needed to form real images at the detection section of the apparatus. The system is capable of measuring the MTF in monochromatic and white light, at any target azimuth, across the field of view, and through focus. The target system contains 14 square-wave gratings with spatial frequencies that range from 2.5 to 156 cpd. Images of these gratings are scanned across a slit. The output data are fed to a first-order recursive digital Butterworth bandpass filter for MTF analysis. The apparatus is diffraction limited at f/31.4. Therefore, it negligibly affects the measurement of the MTF of telescopes and telemicroscopes tested with exit pupils of up to 6.4 mm.

Equipment Design↗
PubMed1988

Modulation transfer functions of low power telescopes.

The modulation transfer functions (MTF's) of 131 low power Galilean and Pechan roof prism Keplerian telescopes comprising 20 models from 7 vendors were measured. MTF results are compared according to model, by type (Galilean or Keplerian), and magnification. Measurements were made on-axis and at the +/- 0.7 field angles. In addition to measuring tangential and radial MTF's some devices were tested with target grating azimuths of 45 degrees and 135 degrees. We also measured the effect of 3 and 6.4 mm exit pupil diameters on the MTF, and compared a color-corrected with a non-color-corrected design in monochromatic and white light. Galilean telescopes exhibited superior MTF's compared to Keplerian designs. The MTF's of Galilean telescopes tested on-axis with vertical and horizontal gratings were equivalent, as expected of rotationally symmetrical devices. However, similarly tested Keplerian telescopes exhibited significantly higher MTF's with vertical gratings. Tests at +/- 0.7 field angles showed that the tangential MTF's of Galilean telescopes were consistently poorer than radial MTF's, but the opposite was true for Keplerian telescopes. The comparatively poorer results obtained with the Keplerian telescopes are due to image doubling and deviation errors of the roof prisms that are dependent on the azimuthal orientation of the prism roof edge. Failure to adopt and maintain the same orientation of hand-held prism monoculars may result in experiencing a variable sharpness of image each time that they are used. Prism deviations of binocular devices must be controlled to avoid vertical disparities.

Lenses↗
PubMed1988

Marriage in a young adult mentally retarded population.

Marriage was examined in a total population of mentally retarded young adults born in a 5-year period. No one with severe retardation had married. Among the mildly retarded, significantly fewer young people had married by age 22 than in a nonretarded comparison population, and the retarded young people who had married had significantly higher IQs than the remainder of the mildly retarded population. The retarded females had significantly more problems in their marriages than nonretarded comparisons. Nevertheless, the marriages of almost half the mildly retarded young women appeared to be working out well. The retarded young men were not significantly different from nonretarded comparisons. Marriages in which both partners were retarded had many problems.

Adult↗
PubMed1988

Peer relationships of mildly retarded young adults living in the community.

Socializing with peers and opposite-sex relationships were examined in two subsets of a mildly mentally retarded (MMR) young adult population living in the community: those who were no longer receiving MR services and those who were attending day centres for MR adults. The MMR young people not receiving services had fewer best friends and socialized significantly less often than a nonretarded comparison population. The MMR males not receiving services also had fewer opposite-sex relationships than comparisons but this difference was not significant for the females. At age 22, these MMR young people continued to see friends from school significantly less often than comparisons, indicating a possible detrimental effect of special schooling on later socializing with peers. The MMR young people at the day centres socialized more often but this was done almost wholly with others who were MR. Within the MMR study population, the young women not receiving services socialized with peers the least, less than the young women at the day centres and less than the young men not receiving services, but they were married most often.

Adult↗
PubMed1988

Benign familial leukopenia and neutropenia in different ethnic groups.

Benign hereditary leukopenia-neutropenia has been reported in several ethnic groups, including Yemenite Jews, Blacks of South African extraction, West Indians and Arab Jordanians. The subjects with BFL were shown not to have an increased incidence of infections, and their response to infection did not differ from subjects having normal white blood cell counts. This study entails the report of two additional unrelated ethnic groups with familial neutropenia - Black Beduin and Falashah Jews. The familial nature of the phenomenon was confirmed. The suggested mechanism of this type of neutropenia is a defect in release of mature WBC from the bone marrow to the peripheral circulation. All ethnic groups thus far reported have tanned or dark skin. The significance of this common feature has still to be elucidated.

Adolescent↗
PubMed1988

Gonadal function in patients with beta thalassaemia major.

Endocrine studies were made on 23 female patients aged 13 to 29 years, with delayed puberty or primary amenorrhoea and beta thalassaemia major, and 12 healthy controls, of whom six were prepubertal and six were in Tanner's stage 3-4. Each patient and control received a single intravenous dose of 100 micrograms gonadotrophin releasing hormone (GnRH), and one week later, 10 U/kg body weight of human menopausal gonadotrophin (hMG) to stimulate ovarian function. The patients had decreased gonadotrophin reserves when compared with those of normal controls, only one of 23 patients had an intact luteinising hormone and follicle stimulating hormone response. Most of the thalassaemic patients with delayed puberty showed normal gonad response to human menopausal gonadotrophin (hMG), but three had very low responses, when compared with that of controls. The gonadal failure was even more severe in four of six patients with primary amenorrhoea. It is important to assess hypothalamic-pituitary-gonadal function in young women with beta thalassaemia major, so that those with glandular dysfunction may be started on replacement therapy.

Adolescent↗
PubMed1988

Hypothalamic-pituitary-gonadal axis in thalassemic patients with secondary amenorrhea.

Eight thalassemic patients, aged 24-35 years, who developed amenorrhea 2-15 years after menarche, were studied. Mean basal serum LH and FSH levels and the peak levels after gonadotropin-releasing hormone were significantly less than corresponding values in normal controls. All patients showed low basal serum levels of estradiol and six had a poor or absent response to human menopausal gonadotropin. One subject had intact pituitary-gonadal function and one patient had an impaired LH and FSH response to gonadotropin-releasing hormone in the presence of a significant increase of estradiol after human menopausal gonadotropin stimulation. The findings regarding pituitary hormones other than gonadotropins suggest that iron overload damages tropic cells unequally and inconsistently. We conclude that both pituitary and gonadal damage may be responsible for the secondary amenorrhea in thalassemic patients.

Adult↗
PubMed1988

Intermittent weekly contraction monitoring to predict preterm labor in low-risk women: a blinded study.

To assess the predictive value of uterine activity as a marker for subsequent preterm labor, 139 black, inner city women were monitored at least three times for 1 hour between 28-32 weeks' gestation using a portable tocodynamometer. All had singleton gestations and gave no previous history of preterm labor or delivery. They were monitored between 8 and 10 AM while sitting in the clinic waiting area. Uterine activity records, numbered randomly, were transmitted by telephone to a site remote from the hospital. No one having any clinical contact with the participants saw or received feedback regarding the contraction data. Tocodynamometry records were then mailed to another center where they were read by one investigator blinded to all clinical information. The mean contraction frequency during the single hour of weekly testing was significantly greater for the 16 women who developed preterm labor than for women who delivered at term at each point between weeks 28-32. Using greater than six contractions per hour on at least one occasion between 28-32 weeks' gestation as a predictor would have identified 12 of 16 women (sensitivity 75%) who subsequently developed preterm labor. This contraction frequency was noted in 26 of 123 women (21%) who labored at term (specificity 79%; P = .0003).

Female↗
PubMed1988

Use of the subcutaneous terbutaline pump for long-term tocolysis.

Nine patients in preterm labor requiring long-term tocolysis were managed with subcutaneous terbutaline administered via a portable infusion pump. All had failed oral tocolytic therapy and were therefore faced with prolonged hospitalization. In this feasibility study, the patients were treated at home and monitored with portable tocodynamometers and home nursing visits. Uterine activity data were transmitted via telephone to the study center and terbutaline pump infusion rates were adjusted accordingly. Terbutaline pump therapy consisted of a combination of low-dose continuous basal infusion supplemented with intermittent high-dose boluses. Total daily drug dosage remained exceptionally low (less than 3 mg/24 hours). The mean gestational age at initiation of therapy was 29.6 +/- 3.7 weeks, and pregnancy was prolonged an average of 9.2 +/- 4.3 weeks. The minimum gestational age at delivery was 37.3 weeks. Patient tolerance was excellent and, in a total 394 patient-days of therapy, there were no significant complications. We conclude that the portable subcutaneous terbutaline pump may be a promising new method for long-term outpatient tocolysis in patients who cannot be maintained on oral therapy.

Administration, Oral↗
PubMed1988

Reduction or cessation of fetal movements after administration of steroids for enhancement of lung maturation. I. Clinical evaluation.

Changes in fetal activity ranging from reduction to cessation of fetal movements were observed in patients at the 25th to 34th week of gestation, who were receiving steroids for enhancement of fetal lung maturation. This was a transient phenomenon, and fetal movements returned to normal by 24 h after the last injection of steroids. Concomitantly, during the period of exposure to steroids, we found an increased incidence of nonreactive monitoring patterns on daily analysis of fetal heart monitoring tracing. Although the pathophysiology of these changes is still unclear, we believe that the practical value of this observation is of importance. Reduction or cessation of fetal movements and a nonreactive nonstress test are generally accepted signs of fetal compromise and considered as an indication for termination of pregnancy. In this selective group of patients this is a temporary phenomenon; therefore, conservative management would seem in order.

Betamethasone↗
PubMed1988

Job histories in open employment of a population of young adults with mental retardation: I.

Job histories were obtained for a population of young adults with mental retardation. No one with IQ less than 50 had been in open employment. Persons with mild mental retardation (n = 100) who received no adult services were compared to peers who were not retarded (n = 52) who left school without academic qualifications on a variety of job measures (e.g., unemployment, time out of the labor force, job turnover, level of job skill, and take-home pay). Among the 54 subjects with IQs of 50 or more who received adult services, approximately half had some open employment. Our results provide a less optimistic picture than that given by reviewers of previous research.

Adult↗
PubMed1987

Positron emission tomography assessment of effects of benzodiazepines on regional glucose metabolic rate in patients with anxiety disorder.

Patients with generalized anxiety disorder (n = 18) entered a 21-day, double-blind, placebo-controlled random assignment trial of clorazepate. Positron emission tomography with 18F-deoxyglucose was carried out before and after treatment. Decreases in glucose metabolic rate in visual cortex and relative increases in the basal ganglia and thalamus were found. A correlation between regional changes in metabolic rate and regional benzodiazepine receptor binding density from other human autopsy studies was observed; brain regions highest in receptor density showed the greatest decrease in rate.

Adult↗
PubMed1987

Catecholamine metabolism and disposition in healthy and depressed subjects.

Depressed patients as a group have been found to excrete greater amounts of catecholamines (CAs) and metabolites than healthy control subjects, but these differences were not uniform for all metabolites. Patients may differ from controls in the metabolism and/or disposition of CAs. We analyzed the suggested metabolic-dispositional differences by determining 24-hour urine values for norepinephrine (NE), epinephrine (E), normetanephrine (NM), metanephrine (M), vanillylmandelic acid (VMA), and 3-methoxy-4-hydroxyphenylglycol (MHPG). For each subject, we calculated ratios of CAs or metabolites to an estimate of CA synthesis and determined ratios of CAs and metabolites to each other based on a precursor-product paradigm. The results indicate that as a group, patients have modestly but significantly greater CA synthesis rates than controls; patients excrete disproportionately more NE and E and disproportionately less MHPG relative to estimated CA synthesis, as well as other metabolites, than do controls; in contrast to NE, E, and MHPG, the increased NM, M, and VMA excretion rates by patients are proportional to each other as well as to the increase in CA synthesis; and the differences in NE, E, and metabolite excretion in the patients as a group are due principally to unipolar rather than bipolar depressives. The differences would be expected if patients, relative to controls, released more NE and E into the circulation. These data indicate the need to measure several CAs and metabolites when evaluating differences between groups since the significance of any given metabolite value needs to be examined in the context of total CA and metabolite production and excretion.

Adult↗
PubMed1987

Electronic considerations in the mutagenesis of some 4,5-bridged chrysenes.

The mutagenic activity of four 4,5-bridged chrysene derivatives, benz(a)aceanthrylene, and 5-methylchrysene was examined using histidine auxotrophic strains TA98 and TA100 of Salmonella typhimurium. All compounds showed a positive mutagenic response with both TA100 and TA98 in the presence of S-9. A correlation between the electronic character of the bridging group and mutagenic activity for the chrysene derivatives is proposed.

Biotransformation↗
PubMed1987

Carcinoma of the prostate clinically and radiologically simulating malignant lymphoma.

A 65-year-old man presented with supraclavicular, mediastinal, and retroperitoneal lymphadenopathy clinically thought to be due to malignant lymphoma. Biopsy of a supraclavicular lymph node revealed metastatic adenocarcinoma positive for prostatic-specific antigen. This site of the primary tumor was confirmed by needle biopsy of the prostate gland. The tumor regressed dramatically following treatment with estramustine phosphate.

Adenocarcinoma↗
PubMed1987

Umbilical and uterine flow velocity waveforms in pregnancies complicated by major fetal anomalies.

A continuous wave Doppler unit was used to obtain umbilical and uterine artery flow velocity waveforms in pregnancies complicated by a major fetal abnormality. A total of 139 examinations were performed on 32 women between 26 to 41 weeks' gestation, and the records were reviewed to determine the changes associated with fetal malformation. The systolic/diastolic (A/B) ratio was used as an index of blood flow resistance in the umbilical artery and the systolic minus diastolic divided by systolic (A-B)/A for the branches of the uterine artery. Seventeen out of 32 patients showed high systolic/diastolic ratio in waveforms taken from the umbilical artery. In 30 out of 32 patients the uterine artery waveform was normal (in two patients the results were equivocal). It appears that a fetal mechanism may determine the changes in the umbilical placental circulation resulting in an umbilical artery pattern of high flow resistance in more than half of the patients with congenital anomalies.

Adult↗