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Biomedical subjects

J Pollack

Publications and source records attributed to J Pollack.

At least 19 recordsLinked to original sources
PubMed1992

"PCL" a new automatic fast reader suitable for in vivo dosimetry.

The authors present a new automatic TLD reader specially designed for medical dosimetric applications, which allow considerable time-saving. The "PCL" reader is based on an isothermal heating kinetics and can be used with TL material of any nature and any shape (powder, microrods, pellets). Doses from 1 microGy to 10 Gy can be measured, or higher doses by interposing an optical absorber in front of the PM. The readout system is controlled by an IBM compatible personal computer. Results can be printed under the form defined by the users and then can be straightly stored in a patient sheet or an experience book. Tests performed with LiF chips TLD 100 and 700 (HARSHAW), Li2B4O7:Mn discs LiB (ALNOR), LiF powder PTL 717 (DESMARQUET) and Li2B4O7:Cu powder (CEN-FAR) are presented. They show a good reproducibility and interesting dosimetric properties.

Humans↗
PubMed1991

Ventilatory threshold and maximal oxygen uptake during cycling and running in female triathletes.

Maximal oxygen uptake (VO2max) and the ventilatory threshold (Tvent) were measured during cycle ergometry (CE) and treadmill running (TR) in a group of 10 highly trained female triathletes. Tvent was defined as the VO2 at which the ventilatory equivalent for oxygen increased without a marked rise in the ventilatory equivalent for carbon dioxide. Female triathletes achieved a significantly higher mean (+/- SE) relative VO2max for running (63.6 +/- 1.2 ml.kg-1.min-1) than for cycling (59.9 +/- 1.3 ml.kg-1.min-1). When oxygen uptake measured at the ventilatory threshold was expressed as a percent of VO2max, the mean value obtained for TR (74.0 +/- 2.0% of VO2max) was significantly greater than the value obtained for CE (62.7 +/- 2.1% of VO2max). This occurred even though the total training time and intensity were similar for the two modes of exercise. Female triathletes had average running and cycling VO2max values that compared favorably with maximal oxygen uptake values previously reported for elite female runners and cyclists, respectively. However, mean running and cycling Tvent values (VO2 Tvent as%VO2max) were lower than recently reported values for single-sport athletes. The physiological variability between the triathletes studied and single-sport athletes may be attributed in part to differences in training distance or intensity, and/or to variations in the number of years of intense training in a specific mode of exercise. It was concluded that these triathletes were well-trained in both running and cycling, but not to the same extent as female athletes who only train and compete in running or cycling.

Adult↗
PubMed1991

Brief psychotherapy of personality disorders.

Thirty-two patients with personality disorder diagnoses were randomly assigned to two treatment conditions that vary on several techniques of brief dynamic psychotherapy. Seventeen patients constituted a waiting list control group. The two brief psychotherapies showed significant improvement on target complaints, SCL-90, and Social Adjustment Scale-SR compared with the control subjects. The two therapy groups were similar in overall outcome but showed interesting differences on several subscale measures. Process measurements of videotaped sessions revealed significant variations in frequencies of therapist interventions across the two treatment conditions, which validated planned differences in the treatment techniques.

Cognitive Behavioral Therapy↗
PubMed1990

Change in patient affect/defense ratio from early to late sessions in brief psychotherapy.

The current study examined changes in the ratio of patients' affective and defensive behaviors during the course of brief psychodynamic psychotherapy. Treatments of 16 patients were videotaped. For each patient, four sessions were evaluated with a minute-by-minute coding system of process variables. When patients were grouped according to outcome scores, significant differences between the high outcome and the average-to-low outcome groups emerged. During the early phase of treatment, patients in both groups showed an average of one affective response per five defensive responses. By the late phase of treatment, the high outcome patients showed a marked shift to one affective response per two defensive responses, while the low outcome patients remained the same. An incidental finding was a negative correlation between good outcome and the ratio of defensive behavior to total patient activity.

Affect↗
PubMed1990

Identification of calcium-calmodulin multifunctional protein kinase II in rabbit kidney.

Recent studies have demonstrated that calcium/calmodulin-dependent multifunctional protein kinase II (CaM-KII) inhibits the reconstituted Na(+)-H+ exchanger from the brush border membrane of proximal convoluted tubule of the rabbit kidney. The present studies were undertaken to evaluate the physiological relevance of this finding by establishing the presence of CaM-KII in rabbit kidney and proximal convoluted tubule cells by Northern RNA hybridization analysis to demonstrate the messenger RNA (mRNA) for CaM-KII and by a selective enzymatic assay of CaM-KII using a synthetic peptide substrate. A single 4.9 Kb mRNA was observed on hybridization of total RNA from rabbit kidney cortex and medulla and from an enriched suspension of rabbit kidney proximal convoluted tubules with a cDNA for rat brain CaM-KII. An enzyme assay using a synthetic peptide substrate representing the site phosphorylated by CaM-KII on glycogen synthase demonstrated calcium-calmodulin dependent protein kinase activity in both rabbit kidney cortex (specific activity of 662 +/- 127 nmol.min-1.mg protein-1) and proximal tubule cells (546 +/- 77 nmol.min-1.mg protein-1). These data establish the presence of CaM-KII in the rabbit kidney, and suggest a role for this enzyme in the control of renal electrolyte transport.

Animals↗
PubMed1990

Cloning and characterization of RNA polymerase core subunits of Chlamydia trachomatis by using the polymerase chain reaction.

Taking advantage of sequence conservation of portions of the alpha, beta, and beta' subunits of RNA polymerase of bacteria and plant chloroplasts, we have designed degenerate oligonucleotides corresponding to these domains and used these synthetic DNA sequences as primers in a polymerase chain reaction to amplify DNA sequences from the chlamydial genome. The polymerase chain reaction products were used as a probe to recover the genomic fragments encoding the beta subunit and the 5' portion of the beta' subunit from a library of cloned murine Chlamydia trachomatis DNA. Similar attempts to recover the alpha subunit were unsuccessful. Sequence analysis demonstrated that the beta subunit of RNA polymerase was located between genes encoding the L7/L12 ribosomal protein and the beta' subunit of RNA polymerase; this organization is reminiscent of the rpoBC operon of Escherichia coli. The C. trachomatis beta subunit overproduced in E. coli was used as an antigen in rabbits to make a polyclonal antibody to this subunit. Although this polyclonal antibody specifically immunoprecipitated the beta subunit from Chlamydia-infected cells, it did not immunoprecipitate core or holoenzyme. Immunoblots with this antibody demonstrated that the beta subunit appeared early in infection.

Amino Acid Sequence↗
PubMed1990

Heat shock response of murine Chlamydia trachomatis.

We have investigated the heat shock response in the mouse pneumonitis strain of Chlamydia trachomatis. The kinetics of the chlamydial heat shock response resembled that of other procaryotes: the induction was rapid, occurring over a 5- to 10-min time period, and was regulated at the level of transcription. Immunoblot analysis and immunoprecipitations with heterologous antisera to the heat shock proteins DnaK and GroEL demonstrated that the rate of synthesis, but not the absolute amount of these two proteins, increased after heat shock. Using a general screen for genes whose mRNAs are induced by heat shock, we identified and cloned two of these. DNA sequence analysis demonstrated that one of the genes is a homolog of dnaK. Further sequence analysis of the region upstream of the dnaK gene revealed that the chlamydial homolog of the grpE gene is located just adjacent to the dnaK gene. The second locus encoded three potential nonoverlapping open reading frames. One of the open reading frames was 52% homologous to the ribosomal protein S18 of Escherichia coli and thus presumably encodes the chlamydial homolog. Interestingly, this ribosomal protein is not known to be induced by heat shock in E. coli. S1 nuclease and primer extension analyses located the start site of the dnaK transcript to the last nucleotide of the grpE coding sequence, suggesting that these two genes, although tandemly arranged, are transcribed separately. No promoter sequences resembling the E. coli consensus heat shock promoter could be identified upstream of either the C. trachomatis dnaK, grpE, or S18 gene. The induction of the dnaK and S18 mRNAs by heat shock occurred at a transcriptional level; their induction could be blocked by rifampin. The mechanisms of induction for these two loci were not the same, however; they were differentially sensitive to chloramphenicol. Whereas the induction of dnaK mRNA required de novo protein synthesis, the induction of the S18 mRNA did not. Thus, C. trachomatis utilizes at least two different pathways to induce the transcription of mRNAs encoding proteins induced in the heat shock response.

Amino Acid Sequence↗
PubMed1990

Ventilatory threshold and maximal oxygen uptake during cycling and running in triathletes.

VO2max and the ventilatory threshold (Tvent) were measured during cycle ergometry (CE) and treadmill running (TR) in a group of 10 highly trained male triathletes. Tvent was indicated as the VO2 at which the ventilatory equivalent for oxygen increased without a marked rise in the ventilatory equivalent for carbon dioxide. Triathletes achieved a significantly higher VO2max for TR (75.4 +/- 7.3 ml.kg-1.min-1) than for CE (70.3 +/- 6.0 ml.kg-1.min-1). Mean CE VO2max was 93.2% of the TR value. Average VO2max values for CE and TR compared favorably with values reported for elite single-sport athletes and were greater than those previously reported for other male triathletes. CE Tvent occurred at 3.37 +/- 0.32 l.min-1 or 66.8 +/- 3.7% of CE VO2max, while TR Tvent was detected at 3.87 +/- 0.33 l.min-1 or 71.9 +/- 6.6% of TR VO2max. The VO2 (l.min-1) at which Tvent occurred for TR was significantly higher than for CE (P less than 0.001). Although the VO2 values at TR Tvent expressed as a percentage of VO2max were consistently higher than for CE, the difference between the means did not reach statistical significance (P greater than 0.05). The average Tvent for CE (as %VO2max) was nearly identical to Tvent values reported in the literature for competitive male cyclists, whereas TR Tvent was lower than recently reported values for elite distance runners and marathoners. We speculate that triathlon training results in general (cross-training) adaptations which enhance maximal oxygen uptake values, whereas anaerobic threshold adaptations occur primarily in the specific muscle groups utilized in training.

Bicycling↗
PubMed1989

The time limit in brief psychotherapy.

The time limit in psychoanalytically oriented brief psychotherapy has been construed as a motivation for the patient and the therapist to work more efficiently in therapy and as a stimulation of the patient's unconscious conflicts relating to separation and loss. The authors show that the time limit, in addition to the above functions, affects all focal conflicts in brief psychotherapy, whether or not they relate to separation issues. The time limit helps both patient and therapist to examine aspects of the patient's focal conflicts that tend to perpetuate symptoms or maladaptive patterns of behavior--that is, the primary gain of the symptom--and may therefore play a crucial role in the efficacy of brief psychotherapy. The authors also discuss implications for technique.

Conflict, Psychological↗
PubMed1987

The sex-determining region of the human Y chromosome encodes a finger protein.

The presence or absence of the Y chromosome determines whether a mammalian embryo develops as a male or female. In humans, genetic deletion analysis of "sex-reversed" individuals has identified a small portion of the Y chromosome necessary and sufficient to induce testicular differentiation of the bipotential gonad. We report the cloning of a 230-kilobase segment of the human Y chromosome that contains some or all of the testis-determining factor gene (TDF), the master sex-determining locus. The cloned region spans the deletion in a female who carries all but 160 kilobases of the Y. Certain DNA sequences within this region were highly conserved during evolution; homologs occur on the Y chromosomes of all mammals examined. In particular, homologous sequences are found within the sex-determining region of the mouse Y chromosome. The nucleotide sequence of this conserved DNA on the human Y chromosome suggests that it encodes a protein with multiple "finger" domains, as first described in frog transcription factor IIIA. The encoded protein probably binds to nucleic acids in a sequence-specific manner, and may regulate transcription. Very similar DNA sequences occur on the X chromosome of humans and other mammals. We discuss the possibility that the Y-encoded finger protein is the testis-determining factor, and propose models of sex determination accommodating the finding of a related locus on the X chromosome. The presence of similar sequences in birds suggests a possible role not only in the XX/XY sex determination system of mammals, but also in the ZZ/ZW system of birds.

Amino Acid Sequence↗
PubMed1987

Spontaneous bilateral pneumothorax in an infant with bronchiolitis.

Spontaneous pneumothorax is an uncommon complication of bronchiolitis due to respiratory syncytial virus. Bilateral spontaneous pneumothorax in an infant with respiratory syncytial virus bronchiolitis has not been previously reported. We report the case of a four-month-old infant who presented in respiratory distress owing to respiratory syncytial virus bronchiolitis with bilateral pneumothoraces. The infant improved with evacuation of air from the chest.

Bronchiolitis, Viral↗
PubMed1987

Isolation and characterization of mutants of Streptococcus mutans using selective removal of wild-type cells by agglutination with an agglutinin from Persea americana.

Persea americana agglutinin (PAA), a substance known to bind basic proteins and inhibit the sucrose-independent adherence of Streptococcus mutants to saliva = coated hydroxyapatite (Staat et al., 1980) was used to selectively enrich for mutants defective in a variety of cell surface associated virulence characteristics from cultures UAB62 (PS14 Riff, serotype c), UAB66 (6715 Strr Spcr, serotype g) and UAB77 (GS5, serotype c). Following mutagenesis and growth for segregation and phenotypic expression, washed cells of each strain were exposed to PAA overnight at 37 degrees C. Aggregated cells were removed by low-speed centrifugation and cells remaining in the supernatant fluids were concentrated, grown to stationary phase and the enrichment with PAA repeated. Mutants isolated following enrichment were phenotypically diverse and included strains defective in one or more of the following characteristics: adherence to glass in a sucrose-containing medium, aggregation with sucrose, dextran or PAA. dextranase production, colony morphology, cell or chain morphology, fermentation of sorbitol, lactose, galactose, raffinose, melibiose, or fructose, and production of surface protein antigen A (SpaA). The diversity of mutant phenotypes identified along with the observation that PAA could still cause aggregation (with a lower efficiency) of all mutants leads us to infer that the interaction of this agglutinin with proteins on the S. mutans cell surface is relatively nonspecific and that the observed inhibition of S. mutants attachment to saliva-coated hydroxyapatite caused by PAA is not due to a highly specific unique interaction of PAA with the protein(s) responsible for sucrose-independent adherence.

Agglutination↗
PubMed1986

Long-term endocrine sequelae after treatment of medulloblastoma: prospective study of growth and thyroid function.

Endocrine evaluations were performed prospectively in 22 patients with medulloblastoma (ages 2 1/2 to 23 1/2 years at diagnosis), after craniospinal radiation with or without adjuvant chemotherapy. The mean craniospinal hypothalamic-pituitary). and thyroid radiation doses were 3600 and 2400 rads, respectively. Fourteen (73%) of 19 patients who had not yet completed their growth experienced a decrease in growth velocity. However, only three of 10 of these children, who underwent growth hormone stimulation tests, had evidence of deficient growth hormone responses, suggesting that growth hormone secretory or regulatory dysfunction, rather than absolute growth hormone deficiency, is present in the majority of these children. Elevated thyroid-stimulating hormone levels were noted in 15 of 22 patients; one patient had hypothalamic hypothyroidism. Thus, the late effects of therapy for medulloblastoma include frequent endocrine morbidity involving hypothalamic-pituitary and thyroid dysfunction.

Adolescent↗
PubMed1979

Lymphosarcoma of the duodenum associated with carcinoma of the lung. Five-year survival.

The case presented describes a patient with lymphosarcoma of the duodenum associated with carcinoma of the lung. This emphasizes the basic problems which lymphosarcoma of the duodenum presents. They are vague symptoms until late in the course of the disease, the absence of early physical findings, the difficulty in interpretation of radiological studies and the frequent association with other primary malignancies elsewhere.

Adenocarcinoma, Bronchiolo-Alveolar↗