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Biomedical subjects

E Katz

Publications and source records attributed to E Katz.

At least 145 records · Page 8Linked to original sources
PubMed1991

A high-performance system for automation of the polymerase chain reaction.

A high-performance PCR system has been developed which reduces the time required for PCR, increases the throughput, reduces reagent consumption and ensures reproducibility of amplification. Integration of sophisticated temperature control with optimally designed vessels has resulted in an amplification system which produces unique benefits. These include rapid amplification, the elimination of the need for oil, even for small volumes, and a microplate format which provides liquid handling automation benefits.

Automation↗
PubMed1991

Increased circulating levels of bromocriptine after vaginal compared with oral administration.

OBJECTIVE: To compare the circulating levels of bromocriptine after oral and vaginal administration of the drug. DESIGN: Experimental PARTICIPANTS: Seven ovulatory female volunteers and one hyperprolactinemic patient. INTERVENTIONS: Ovulatory volunteers were randomized to receive either oral or vaginal bromocriptine (2.5 mg). In a second session, the subjects were crossed-over to bromocriptine by the alternate route. An additional hyperprolactinemic patient received vaginal bromocriptine only. MAIN OUTCOME MEASURE: Serum bromocriptine and prolactin (PRL) levels were measured hourly for 12 hours in the normal volunteers and for 10 hours in the hyperprolactinemic patient. RESULTS: Circulating bromocriptine levels were significantly higher after vaginal bromocriptine after the 7th hour (P less than 0.05). The reduction in serum PRL was significantly greater after oral administration between 2 and 6 hours. CONCLUSIONS: Vaginally administered bromocriptine may result in a reduction in the overall dose required, thereby improving compliance without compromising therapeutic efficacy.

Administration, Oral↗
PubMed1990

Experimental model of acute appendicitis in the rabbit with determination of leucine amino peptidase (LAP) and acid phosphatase (acid-P) activities in portal blood samples.

The activities of leucine amino peptidase (LAP) and acid phosphatase (Acid-P), conceivable markers of acute appendicitis, were determined in the portal blood of rabbits with acute appendicitis. An experimental model of acute appendicitis was established using No.-O silk ties to block the base of the appendix. The clinical and histopathological picture of acute appendicitis was seen after 12 hr in all the rabbits in the model group (9/9) and in none of the control group. Catheterization of the superior mesenteric vein was performed in rabbits with acute appendicitis, and portal blood samples were taken at 0, 6, and 12 hr for assay of LAP and Acid-P activities. No statistically significant difference between the experimental group and the control group, in the activities of LAP and Acid-P, was found at any time interval. The experimental model of acute appendicitis in the rabbit which is described here is simple and carries a high rate of success. This is probably the first report of using continuous catheterization and repeated sampling of portal blood, for the measurement of enzyme activities, in an experimental model of acute appendicitis. It was concluded that serum LAP and Acid-P activities cannot be used as markers for acute appendicitis.

Acid Phosphatase↗
PubMed1990

Spatial and temporal analysis by neurons in the representation of the central visual field in the cat's lateral suprasylvian visual cortex.

We studied quantitatively the receptive-field properties of 74 units recorded from the representation of the central visual fields in the cat's lateral suprasylvian (LS) visual cortex. In agreement with previous workers, we found that LS receptive fields tended to be large and to lack discernible spatial structure. They resembled the complex receptive fields of areas 17 and 18 in their general organization. We examined the responses of these neurons to moving optimally oriented sinusoidal gratings that varied in spatial and temporal frequency of drift. Most LS neurons were selective for the spatial frequency of sinusoidal gratings; 7% responded to all spatial frequencies below a cutoff value. In agreement with previous reports, the optimal spatial frequencies for LS neurons covered a wider range than is seen in either area 17 or 18 alone (0.05-1 cycle/deg), but are certainly included in the range covered by both these afferent areas. Individual neurons in LS responded to a range of spatial frequencies broader than is typical for neurons in areas 17 and 18. The effect of varying the drift rate of otherwise optimal gratings was similar in LS to that reported for areas 17 and 18. Most neurons were optimally responsive to drift rates between 0.5 and 4 Hz, and resolved frequencies as high as 10-30 Hz. A few neurons had optima higher than 6 Hz and resolved frequencies in excess of 30 Hz. We conclude that the receptive fields of LS neurons reflect rather closely the properties of their afferents from areas 17 and 18.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The danger of high compliance balloons for esophageal dilatation in achalasia.

High compliance balloons, commonly used for pneumatic dilatation of achalasia patients, theoretically subject the widened esophageal wall, proximal to the narrow zone, to increased pressure, and subsequently to a higher risk of perforation. The new type of inelastic cylindrically shaped balloons, such as the Gruntzig-type and Rigiflex Achalasia Dilator, seems to be safer, since it increases esophageal wall tension in the stenotic zone only. The purpose of this study was to present a pathophysiological consideration of this assumption, together with two cases which support it.

Adult↗
PubMed1990

Correlation between cutaneous reaction in vaccinees immunized against smallpox and antibody titer determined by plaque neutralization test and ELISA.

The correlation between skin reaction, exhibited by vaccinees immunized against smallpox, and antibody titer determined by plaque neutralization and ELISA, was evaluated. Twenty eight out of 35 young adults (vaccinated at infancy and at the age of 8 years), who were injected with vaccinia virus, displayed a major skin reaction a week later. An increase of four-folds and more, in antibody titer against vaccinia virus, is generally considered positive immunization take-up against smallpox. According to this criterion, only 17 of the vaccinees were found positive by plaque neutralization, while 25 by the indirect micro-ELISA. Thus, there were eight vaccinees who were considered immunized by the ELISA, (seven of them also according to the skin reaction), but not by the plaque neutralization test.

Adolescent↗
PubMed1990

The persistence of neutralizing antibodies after revaccination against smallpox.

Persistence of neutralizing antibodies after revaccination against smallpox was studied. Single serum samples from 140 revaccinated donors were tested for neutralizing antibodies using the plaque reduction assay. The donors, aged 21-49 years at sampling, had been vaccinated in infancy and revaccinated at 8 and 18 years; they formed seven groups of 20 men each, revaccinated about 3, 5, 10, 15, 20, 25, and 30 years before sampling. The differences in mean titer among groups were insignificant (P greater than .01). The titer significantly decreased during the first 3 years after the revaccination but remained stable for at least 30 years thereafter (geometric mean titer, 10.5; 95% confidence interval, 6.8-16.4). The results suggest that there is probably no need for routine revaccinations beyond the primary and two revaccinations; nevertheless, persons at high risk should be revaccinated regardless of their vaccination status.

Adult↗
PubMed1990

Selectivity for orientation and direction of motion of single neurons in cat striate and extrastriate visual cortex.

1. We consider the consequences of the orientation selectivity shown by most cortical neurons for the nature of the signals they can convey about the direction of stimulus movement. On theoretical grounds we distinguish component direction selectivity, in which cells are selective for the direction of movement of oriented components of a complex stimulus, from pattern direction selectivity, or selectivity for the overall direction of movement of a pattern irrespective of the directions of its components. We employed a novel test using grating and plaid targets to distinguish these forms of direction selectivity. 2. We studied the responses of 280 cells from the striate cortex and 107 cells from the lateral suprasylvian cortex (LS) to single sinusoidal gratings to determine their orientation preference and directional selectivity. We tested 73 of these with sinusoidal plaids, composed of two sinusoidal gratings at different orientations, to study the organization of the directional mechanisms within the receptive field. 3. When tested with single gratings, the directional tuning of 277 oriented cells in area 17 had a mean half width of 20.6 degrees, a mode near 13 degrees, and a range of 3.8-58 degrees. Simple cells were slightly more narrowly tuned than complex cells. The selectivity of LS neurons for the direction of moving gratings is not markedly different from that of neurons in area 17. The mean direction half width was 20.7 degrees. 4. We evaluated the directional selectivity of these neurons by comparing responses to stimuli moved in the optimal direction with those elicited by a stimulus moving in the opposite direction. In area 17 about two-thirds of the neurons responded less than half as well to the non-preferred direction as to the preferred direction; two-fifths of the units responded less than one-fifth as well. Complex cells showed a somewhat greater tendency to directional bias than simple cells. LS neurons tended to have stronger directional asymmetries in their response to moving gratings: 83% of LS neurons showed a significant directional asymmetry. 5. Neurons in both areas responded independently to each component of the plaid. Thus cells giving single-lobed directional-tuning curves to gratings showed bilobed plaid tuning curves, with each lobe corresponding to movement in an effective direction by one of the two component gratings within the plaid. The two best directions for the plaids were those at which one or other single grating would have produced an optimal response when presented alone.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Treatment of fistulas of the biliary tract by endoscopic insertion of endoprostheses.

Five patients with fistulas of the biliary tract are reported; three had fistulas caused by operative injury and two, by accidental blunt abdominal trauma. All patients were treated successfully by endoscopic transpapillary insertion of biliary endoprostheses. The endoprostheses were removed after four to 17 weeks in all patients, and no evidence of biliary leakage was revealed by repeat cholangiograms and other clinical follow-up study. This effective, simple and safe method allows the fistula to heal and is a good alternative to surgical treatment.

Adolescent↗
PubMed1990

Acute surgical abdominal disease in chronic schizophrenic patients: a unique clinical problem.

From our experience with chronic schizophrenic patients treated for acute intra-abdominal surgical disease, we present seven examples of this unique clinical condition. In all seven cases the decision to operate was preceded by considerable delay, owing to misleading medical history, patient behavior, and the lack of definitive signs of peritonitis. The intra-operative findings were unexpected, and in all cases the disease had reached an advanced stage. As chronic schizophrenic patients have a distorted perception of pain and seldom demonstrate a clinical picture commensurate with the disease, we advocate that a higher index of suspicion be assigned to these patients than to the average acutely ill patient.

Abdomen, Acute↗
PubMed1989

[Papillary cystic neoplasm of the pancreas].

Papillary cystic neoplasm of the pancreas, usually found in the tail, is a relatively benign tumor that occurs predominantly in young women. We report a 17-year-old girl admitted for investigation of an abdominal mass found on routine examination. At operation a 12 cm solid mass was found originating from the tail of the pancreas. Distal pancreatectomy was performed and histopathological examination revealed a solid papillary cystic tumor.

Adolescent↗
PubMed1989

[Repair of large abdominal wall defects with expanded polytetrafluoroethylene].

Most abdominal wall defects can be repaired by primary closure. However, when the defect is so large that there is tension on closure, use of prosthetic material is indicated. Expanded polytetrafluoroethylene has the advantages of low rates of infection, foreign body reaction and adhesion formation, making it the material of choice for repair of large abdominal wall defects.

Abdominal Muscles↗
PubMed1989

[Swallowed toothbrush: an indication for immediate endoscopy].

Foreign body ingestion is a common problem encountered in the emergency room. A swallowed toothbrush poses a special problem as it never passes through the GI tract spontaneously. Early endoscopy and removal is recommended. We report a 16-year-old girl who accidentally swallowed a toothbrush which was extracted via endoscopy without complications.

Adolescent↗