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Biomedical subjects

J Hirsch

Publications and source records attributed to J Hirsch.

At least 235 records · Page 13Linked to original sources
PubMed1983

Two nonassociative components of the proboscis extension reflex in the blow fly, Phormia regina, which may affect measures of conditioning and of the central excitatory state.

With the use of controls not included in previous studies, evidence is presented for the existence of water-induced central excitatory state (w-CES) from analyses of pure-breeding high- and low-CES lines in the blow fly, Phormia regina. The CES lines differed in base-level responsiveness to distilled water (and to saline) as well as in response levels for w-CES and for sucrose-induced CES, which suggests the existence of genetic correlates for several components of the proboscis extension reflex. Recognition of several nonassociative components complicates the interpretation of individual scores in earlier studies of proboscis extension conditioning and of the central excitatory state.

Animals↗
PubMed1983

Effects of severe long-term food deprivation and refeeding on adipose tissue cells in the rat.

To determine whether it is possible to use diet to cause a loss of adipocytes, adipose tissue cellularity was examined in adult male rats subjected to unusually prolonged semistarvation. After 1 wk of total fast, rats were given a nutritionally inadequate glucose-electrolyte diet for up to 7 wk. This caused a 49% reduction of body weight, up to a 99% reduction in the weight of adipose tissue, and significant losses of total adipose tissue DNA content. Nevertheless, there was no evidence that fat cells had been lost. The number of fat cells in the right epididymal depots of the food-deprived rats equaled both the number seen in left depots after refeeding and the number seen in corresponding depots of nonfasted controls. Adipose tissue DNA synthesis, which declined 88% below control values during fasting, did increase as much as 2,000% above control values during refeeding. However, autoradiographs showed that the increase reflects only the replacement of lost endothelial and nonadipocyte mesenchymal cells; no labeled fat cell nuclei were found. Thus, severe, long-term food deprivation followed by refeeding causes loss and recovery of stromal-vascular cells in adipose tissue but no loss of fat cells.

Adipose Tissue↗
PubMed1983

The diagnosis of acute, recurrent, deep-vein thrombosis: a diagnostic challenge.

Recurrent venous thrombosis presents a diagnostic challenge. Venography, impedance plethysmography and fibrinogen leg scanning all have potential limitations, and their role in this context has not been evaluated. We performed a prospective cohort study evaluating impedance plethysmography and leg scanning, plus venography, using outcome on long-term follow-up as the end point in 270 patients with clinically suspected recurrent deep-vein thrombosis. Anticoagulant treatment was withheld in the 181 patients negative by noninvasive testing and was given in patients positive by impedance plethysmography if leg scanning was positive or if intraluminal filling defects were detected by venography. The validity of this approach was tested by long-term follow-up. Three of 181 patients (1.7%) negative by noninvasive testing had a recurrence, compared with 18 of 89 (20%) with positive findings (p less than 0.001). Our objective diagnostic approach has high clinical utility; an objective rationale for withholding or giving treatment was established in 95% of patients.

Acute Disease↗
PubMed1982

A virally induced obesity syndrome in mice.

An obesity syndrome was found in a number of mice infected as young adults with canine distemper virus, a morbillivirus antigenically related to measles. Body weights of obese animals 16 to 20 weeks after infection were comparable to those reported for genetically obese mice and for mice rendered obese by hypothalamic lesions. The total number of adipocytes in specific fat deposits was greater in obese animals than in their lean littermates. This hyperplasia was accompanied by moderate cell enlargement. Pancreatic islet tissue was also hypercellular in the obese mice. Brain tissue from the obese mice showed no overt pathology, and immunofluorescence staining for viral antigens was negative. There may be a selective, virus-induced disruption of critical brain catecholamine pathways.

Adipose Tissue↗
PubMed1982

[Leg disorders--disorders of blood supply. The effect of Essaven ultra in chronic venous insufficiency].

An open controlled study was performed over a period of 8 weeks to evaluate the effect of Essaven ultra capsules versus placebo in a total of 60 patients suffering from chronic venous insufficiency. Statistical analysis was performed on 29 patients on the active drug (one dropout) and on 25 patients on placebo (5 dropouts). Apart from patients' statements circumference measurements taken of 3 leg segments were used to assess the results of the treatment. In the patients on the active drug there were significant reductions of circumference in the three leg segments (ankle, calf and knee joint) while, in part of the patients on placebo, leg circumference was significantly increased. In the group on active treatment subjective symptoms were also significantly improved in comparison with the controls. The test drug was very well tolerated.

Anthropometry↗
PubMed1982

Simultaneous recognition of two spatial-frequency components.

A two-frequency two-response paradigm was employed. The stimulus on any trial was a compound grating containing two sinusoidal components of different spatial frequencies where the contrast in one or both components could be zero. The observer gave two responses each indicating confidence that one of the two components had been presented with contrast greater than zero. If these responses are assumed to be related to outputs of spatial-frequency channels according to specified recognition linking hypotheses, then channel properties such as bandwidth, negative influences, correlation of noise, and additivity can be inferred. Possible modifications of spatial frequency channel models are discussed.

Form Perception↗
PubMed1982

Central excitation in the fruit fly (Drosophila melanogaster).

The probability of proboscis extension to a water posttest is increased by prior sucrose stimulation. This phenomenon, termed the central excitatory state (CES), first described in Phormia regina, has now been characterized in Drosophila melanogaster. Drosophila's CES (a) decays over time and (b) is a function of sucrose concentration. THe test for CES also measures water responsiveness, a component of proboscis extension operationally independent of CES. Control experiments confirmed that CES-dependent proboscis extension is not an artifact due to restimulation of sucrose residues and that the neural junctures involved are centrally located.

Animals↗
PubMed1982

Responsiveness of Phormia regina to saline.

Studies by Nelson (1971), Hirsch and McCauley (1977), and McGuire and Hirsch (1977) with the blow fly, Phormia regina, have reported evidence for conditioning. With respect to relative responsiveness to water or saline in the first position of the serial compound stimulus arrangement used, however, the evidence was inconsistent. These experiments show the effect on such responsiveness of the (a) method of mounting and (b) deprivation and satiation procedures. It is also possible that P. regina actively control internal ion concentration by saline intake.

Animals↗
PubMed1982

Oculomotor functions in reading disability.

Oculomotor functions and information processing systems from a complex interaction in the achievement of reading skills, This study was designed to determine the relation between oculomotor functions and reading ability in fourth and sixth grade children. Four oculomotor functions were measured during the reading of digits and prose. The oculomotor functions were used independently and collectively to predict reading ability under both reading conditions. These relations were then examined with and without removal of the influence of verbal intelligence. The results indicate that when examined collectively, oculomotor functions are related to reading ability, but when oculomotor functions are examined independently, only marginally significant relations appear. Similar relations were found for both age groups. Verbal intelligence influenced some of the individual relations. The individual oculomotor functions that appeared responsible for the collective relation were frequency of fixations and lag of accommodation. A reciprocal-causation model between reading ability and oculomotor functions is proposed.

Accommodation, Ocular↗
PubMed1982

Limits of spatial-frequency discrimination as evidence of neural interpolation.

We have studied the ability of observers to discriminate between suprathreshold vertical sinusoidal spatial-frequency gratings on the basis of spatial frequency. The results show that spatial-frequency discrimination is not a smooth function of spatial frequency but instead appears regularly segmented. Similar results were also obtained in an experiment in which observers discriminated between pairs of narrow vertical lines on the basis of their separation. Angular resolutions achieved for both discrimination tasks were less than the spacing between photo-receptors, requiring some type of neural interpolation. The similarity between the two sets of data indicates that discrimination between spatial-frequency gratings is probably based on the separation between two features exactly one cycle apart. We suggest that the segmentation reflects the existence of neural-image representations with discrete levels of spatial accuracy.

Humans↗
PubMed1982

[Contribution to the true non-African Burkitt's lymphoma (author's transl)].

It is reported on a 6-year-old Middle European boy suffering from a nasopharynx tumor with involvement of a submandibular lymph node. The tumor was classified by morphologic, serologic and virologic data as a true or Epstein-Barr virus-associated Burkitt's lymphoma, resp., which has been, up to now, seldom seen outside Africa. The patient died 3 months after diagnosis. Autopsy has shown tumor involvement of nasopharynx and soft tissues in the left neck region, several lymph nodes, kidneys, liver, spleen, and bone marrow. Cytologic, light and electron microscopic data are reported and the structural change of the tumor is referred to.

Autopsy↗