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Biomedical subjects

S Friedman

Publications and source records attributed to S Friedman.

At least 217 records · Page 12Linked to original sources
PubMed1992

Progress and survival factors in acute non lymphocytic leukemia. A 15 year analysis.

We analyzed a population of adults with acute non lymphocytic leukemia (ANLL) treated from 1972-1989 to identify prognostic factors and the influence of therapy over time. To 179 patients treated at Sunnybrook Medical Centre (SMC) were added 114 patients from published patient series from Princess Margaret Hospital (PMH) all treated during that period. All PMH and 98 SMC patients received one of three remission induction protocols: CAV (cyclophosphamide, cytosine arabinoside [ara-C], vincristine) 1973-1976 (n = 46); ACT (Adriamycin, ara-C +/- 6-thioguanine) 1976-1983 (n = 83); high dose ara-C and corticosteroids 1983-1987 (n = 83). The remainder either received supportive therapy only or minimally toxic therapy (e.g., low dose ara-C, 6-mercaptopurine) due to presenting complications such as advanced age, severe concurrent medical condition, or most recently at SMC only, mitoxanthrone and ara-C, and were excluded from analysis. Responses obtained at the two institutions were identical, no survival advantage of any particular protocol was seen. Overall median survival was 8.5 months for patients treated on protocol and 20 months for those entering complete remission. Patients treated with supportive or minimally toxic therapy (n = 76) had a median survival of less than two months. In multivariate analysis, the only important factors for survival were complete response to initial therapy; complete response to second induction therapy following either first relapse (n = 89) or lack of complete response to first therapy (n = 15); and normal cytogenetic analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

AIDS outreach workers: an exploratory study of job satisfactions/dissatisfactions.

AIDS outreach workers operate at the frontlines of the AIDS epidemic to provide information and education to high-risk individuals. Recent reports indicate that these workers have been effective in helping to reduce high-risk behaviors. However, a review of retention data for 62 outreach workers employed from 1986 to 1988 at a private nonprofit research institute indicated a high rate of turnover, especially among males. The literature provides little information regarding the demographic characteristics of outreach workers and their sources of job satisfaction and dissatisfaction. This exploratory investigation was undertaken to address these topics. Structured interviews were conducted with 20 currently active outreach workers. Results indicate that altruistic motives were most frequently cited as reasons why people became outreach workers and also provided the primary source of satisfaction. Stress was most frequently mentioned as a source of dissatisfaction and also as a reason previous workers had left outreach work. Conclusions focus on the outreach workers' suggestions for job improvements. These included: improvement in the terms of employment (e.g., salary, benefits); more education and training opportunities; and more support groups or help with recovery.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Effects of CO2 laser irradiation on pulpal blood flow.

CO2 laser may be beneficially applied to teeth in preventive and restorative dentistry, but its physiopathologic effects on the dental pulp have not been reported. To address the dynamic pulpal changes induced by CO2 laser the purpose of this study was to examine such changes in pulpal microcirculation. The enamel surfaces of 4 cat canines were irradiated by CO2 laser beam, delivered by either a handpiece or microslad with a focal spot diameter of 0.21mm and 0.33mm, respectively. Exposure powers of 2.6-20 W were used for durations of 0.05-0.2 sec, resulting in energy density range of 304-1440 J/cm2. Non-invasive measurement of pulpal blood flow (PBF) by a laser Doppler flowmeter was maintained continuously before and following CO2 laser irradiation. CO2 laser irradiation resulted in an immediate increase in PBF, which subsided after 2-3 min. Large pulps responded with a significantly higher PBF increase than small pulps. These results confirm that CO2 laser irradiation of the tooth surface has a thermal effect on the pulp, which is moderated by the insulating capability of dentin. It appears that the associated thermal damage is not extensive when laser exposure parameters are such as used herein.

Animals↗
PubMed1992

Split-liver orthotopic liver transplantation: how to divide the portal pedicle.

It is possible to obtain two good-quality hepatic transplants from a single cadaveric liver by separation of right and left lobes of the liver or section between the left medial segment and the left lateral segment medial to the umbilical cleft. We attempt to define the ideal basis of separation of the structures of the portal pedicle, based on anatomic study of 25 livers. Ideally, the following should be sectioned: the left portal vein, longer and more constant than the right; the right branch of the hepatic artery, larger and more constant than the left; and the left hepatic duct, being aware of the vascularization of the common hepatic duct. Use of the left portal vein necessitates the interruption of all left venous portal branches of segment I, which should be systematically resected. A section between the left medial segment and the left lateral segment interrupts all portal venous branches of the left medial segment, which should then be resected. Before hepatic division, a cholangiogram and arteriogram are indispensable to detect variations and avoid an extensive dissection that may endanger bile duct vascularity.

Bile Ducts↗
PubMed1992

Behavioral effects of oral yohimbine in differentially reared nonhuman primates.

Eight unrestrained macaques were observed for 2 hours following either two oral doses of yohimbine (0.2 mg/kg and 2.0 mg/kg) or placebo administration. Four of the subjects were normally reared and four subjects had early maternal and social deprivation. In the normal subjects, yohimbine, at both doses, produced increased tension and enervation and decreased species-typical "normal" behaviors. In deprivation-reared subjects, low-dose yohimbine produced reductions in tension and enervation, and increases in "normal" behaviors. High doses of yohimbine diminished behavioral score differences between groups. The prominent increases in enervation observed in normally reared subjects suggests that yohimbine is not unequivocally anxiogenic. Moreover, early social deprivation may alter the pattern of response to yohimbine, perhaps as a result of aberrant neurodevelopment. This study reflects the role of experiential factors in determining patterns of affective response to putative anxiogenic agents.

Aging↗
PubMed1992

Is there compensated hypothyroidism in infancy?

The state-mandated newborn thyroid screening program may uncover infants who exhibit normal thyroxine (T4) levels with various degrees of hyperthyrotropinemia. To elucidate further the thyroid status, the basal metabolic rate (BMR) of 10 infants (7 boys, 3 girls; aged 9 to 63 days) was studied by indirect calorimetry. They were clinically euthyroid and healthy with no evidence of overt biochemical hypothyroidism (low T4, high thyroid-stimulating hormone [TSH]). Confirmatory testing indicated that all infants had normal serum T4 levels for age (mean +/- SD: 10.3 +/- 3.2 micrograms/dL). However, serum TSH levels varied from 2.3 to 99.2 microU/mL. In 4 infants (2 boys, 2 girls) the BMR was low (38.1 +/- 4.1 kcal/kg per day), while the other 6 patients (5 boys, 1 girl) demonstrated BMRs within the normal range (49.6 +/- 1.9 kcal/kg per day, P less than .001). The serum TSH levels were above 7.0 microU/mL among those infants with a low BMR, whereas the serum TSH levels were always below 6.0 microU/mL among the normometabolic infants. All infants who had a low BMR received thyroid therapy and promptly became normometabolic (BMR: 48.7 +/- 1.0 kcal/kg per day) with suppression of TSH levels (3.2 +/- 1.3 microU/mL) within 3 weeks of therapy, while their serum T4 levels remained within the normal range. The observed normalization of BMR in parallel to reduction of TSH levels following thyroid replacement therapy strongly suggests that these patients demonstrated a hypometabolic state, despite normal serum T4 levels. Therefore, the assessment of BMR may help define subclinical hypothyroidism in infancy in conjunction with a close monitoring of TSH concentration.

Basal Metabolism↗
PubMed1992

Diabetes and peripheral vascular disease.

The classic Framingham Study suggests that the duration of diabetes is a contributing factor in the development of PVD. The major objective of all podiatric physicians should be to provide patients with the necessary information about the severity of their disease, particularly alerting them that noncompliance may lead to a lower extremity amputation and enlisting them as part of the treatment team in managing their condition.

Diabetic Angiopathies↗
PubMed1991

The core element of the EcoRII methylase as defined by protease digestion and deletion analysis.

Binding of the EcoRII DNA methyltransferase to azacytosine-containing DNA protects the enzyme from digestion by proteases. The limit digest yields a product having a Mr on SDS-PAGE 20% less than the intact protein. The N terminus of the tryptic digestion product was sequenced and found to be missing the N terminal 82 amino acids. Under the conditions used unbound enzyme was digested to small peptides. Protection of the enzyme from protease digestion implies that the enzyme undergoes major conformational changes when bound to DNA. The trypsin sensitive region of the EcoRII methyltransferase occurs prior to the first constant region shared with other procaryotic DNA(cytosine-5)methyltransferases. To determine if this region played a role in substrate binding or specificity, N-terminal deletion mutants were studied. Deletion of 97 amino acids resulted in a decrease of enzyme activity. Further deletions caused a complete loss of activity. Enzyme deleted through amino acid 85 was purified and found to have the same specificity as wild type however there was an increase in Km for both S-adenosylmethionine (AdoMet) and DNA of 27 and 18 fold respectively. The N-terminus of the EcoRII methylase, although a variable region present in many procaryotic DNA(cytosine-5)methylases, plays no role in determining enzyme specificity, although it does contribute to the interaction with both AdoMet and DNA.

Amino Acid Sequence↗
PubMed1991

Inhibition of recA-mediated strand exchange by adducts of azacytosine-containing DNA and the EcoRII methylase.

Wild type Escherichia coli cells containing elevated levels of DNA (cytosine-5)methyltransferases have increased sensitivity to the toxic effects of 5-azacytidine. The methyltransferases form tight binding complexes with azacytosine in DNA which could interfere with the recA recBCD repair pathway which is largely responsible for cell survival after treatment with the drug. We therefore determined if these complexes interfered with recA-mediated strand exchange in vitro. 32P-Labeled DNA fragments containing a single EcoRII site, with cytosine in the (-) strand replaced by 5-azacytosine, were prepared. We investigated the effect of the EcoRII methyltransferase on recA-mediated strand exchange with homologous M13 DNA by electrophoresis in agarose gels. In the absence of the methylase the rate and extent of strand exchange of azacytosine-containing DNA is the same as control DNA. In the presence of the methyltransferase strand exchange is inhibited, but some incorporation of duplexes into recA-single-stranded DNA (ssDNA) complexes still occurs. The formation of these complexes is dependent on the length of the fragment 3' to the methylase binding site on the strand complementary to the ssDNA. The greater the length the greater the number of complexes that form. S-Adenosyl-L-methionine, which enhances binding of the methyltransferase to azacytosine-containing DNA, causes an increase in the inhibition of strand exchange and an increase in the number of inactive complexes formed. The complexes can be dissociated with guanidinium chloride which denatures the methyltransferase and leads to release of the (+) strand. The (-) strand remains associated with the ssDNA. This result implies that a plectonemic joint is formed between recA-ssDNA complexes and azacytosine-containing DNA-methyltransferase complexes. However, branch migration in these complexes is inhibited. Denaturation of the methyltransferase allows branch migration to proceed to completion, releasing the (+) strand.

Cytosine↗
PubMed1991

Dose-response effects of oral yohimbine in unrestrained primates.

Six unrestrained bonnet macaques were each observed after oral administration of four dosages of yohimbine hydrochloride (0.10, 0.25, 0.50, and 0.75 mg/kg) and a placebo. Yohimbine significantly increased episodes of motoric activation and affective response interspersed with intervals of behavioral enervation. Yohimbine scores correlated closely with baseline levels; there was no dose-response relationship. Response to oral yohimbine differed in several ways from subcutaneous and intravenous sodium lactate infusions, including prominent enervative symptoms and the appearance of sexual arousal. In light of the appearance of cyclic enervative episodes, this study suggests limitations to primate models of panic disorder utilizing oral yohimbine.

Administration, Oral↗
PubMed1991

Erythrocyte sedimentation rate predicts early relapse and survival in early-stage Hodgkin disease. The EORTC Lymphoma Cooperative Group.

OBJECTIVE: To assess the value of an elevated (greater than 30 mm/h) Westergren erythrocyte sedimentation rate (ESR) for predicting early relapse and survival after therapy in patients with clinical stage I or II Hodgkin disease. INTERVENTIONS: We studied 772 patients with early-stage Hodgkin disease who had participated in two separate multicenter clinical trials. Both trials used modern field radiotherapy and, in some patients, multi-agent chemotherapy. MAIN RESULTS: The ESR patterns were based on pretherapy and post-therapy assessments: pattern 1, always normal (n = 261); pattern 2, elevated before therapy but normal immediately after therapy (n = 121); pattern 3, elevated before therapy but normal within 3 months after therapy (n = 89); pattern 4, always elevated (n = 48); pattern 5, normal before therapy but oscillating between normal and elevated after therapy (n = 150); pattern 6, elevated before therapy but oscillating between normal and elevated after therapy (n = 130). By multivariate analysis, independent of whether or not patients received chemotherapy in the initial therapy protocol, ESR patterns 4, 5, and 6 were shown to be the best predictors for early relapse and survival when patients were stratified according to the type of chemotherapy received and the number of involved nodal areas. Patients with ESR pattern 4 had a relative risk for death seven times that of patients with patterns 1, 2, or 3. Early relapse was the second most important factor predicting death, irrespective of ESR; patients with early relapse and ESR patterns 1, 2, or 3 had a relative risk for death of 4.5, and those with early relapse and ESR patterns 4, 5, or 6 had a relative risk for death of 15. Whether or not chemotherapy was given initially did not change the relative risk, which shows that ESR, not initial therapy, was the predictor for early relapse and death due to Hodgkin disease. CONCLUSION: An unexplained elevated ESR after therapy, especially after modern radiotherapy, independent of other factors, strongly suggest the presence of aggressive and resistant Hodgkin disease. An elevated ESR is predictive of early relapse and poor prognosis; its presence justifies early aggressive therapy.

Adult↗
PubMed1991

Identification of a highly conserved domain in the EcoRII methyltransferase which can be photolabeled with S-adenosyl-L-[methyl-3H]methionine. Evidence for UV-induced transmethylation of cysteine 186.

DNA methyltransferases can be photolabeled with S-adenosyl-L-methionine (AdoMet). Specific incorporation of radioactivity has been demonstrated after photolabeling with either [methyl-3H]AdoMet or [35S]AdoMet (Som, S., and Friedman, S. (1990) J. Biol. Chem. 265, 4278-4283). The labeling is believed to occur at the AdoMet binding site. With the purpose of localizing the site responsible for [methyl-3H]AdoMet photolabeling, we cleaved the labeled EcoRII methyltransferase by chemical and enzymatic reactions and isolated the radiolabeled peptides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high pressure liquid chromatography. The labeled peptides were identified by amino-terminal sequencing. A common region was localized which accounted for 65-70% of the total label. This region includes a highly conserved core sequence present in all DNA (cytosine 5)-methyltransferases. One such fragment was digested further with chymotrypsin, and amino acid analysis of the resulting 3H-labeled peptide was consistent with the sequence Ala-Gly-Phe-Pro-(Cys)-Gln-Pro-Phe-Ser-Leu. However, the cysteine residue was not recovered as carboxymethylcysteine. The Pro-Cys bond was found to be protected from cleavage at cysteine residues after cyanylation. These results suggest that the cysteine residue is modified by the labeling reaction. The chymotryptic fragment was hydrolyzed enzymatically to single amino acids, and the labeled amino acid was identified as S-methylcysteine by thin layer chromatography. These results indicate that the cysteine residue is located at or close to the AdoMet binding site of EcoRII methyltransferase.

Amino Acid Sequence↗
PubMed1991

Therapeutic implications and sites of relapse predicted by elevated posttherapy erythrocyte sedimentation rate in early stage Hodgkin disease.

An analysis was performed of all 57 early relapses (ER) (within 18 months of therapy initiation) seen in a group of 301 patients treated on three successive European Organization for Research and Treatment of Cancer (EORTC) protocols from 1964 to 1981; to determine whether a posttherapy elevated erythrocyte sedimentation rate (ESR) (greater than or equal to 30 mm) could predict the type of relapse and the effect upon the relapse of different therapies received. Overall most ER occurred in extranodal (EN) (42%) or irradiated transdiaphragmatic nodal (TDN) (40%) sites. Compared to patients with normal posttherapy ESR (n = 12), patients with elevated posttherapy ESR (n = 45) had the same proportions of outfield and late relapses; more frequent multiple sites of ER (38% vs. 25%), increased proportions of early EN relapses (16% vs. 3%), TDN relapses (17% vs. 2%), and other ER (6% vs. 1%). ER were most frequently observed between 1964 and 1971, and "modern" radiotherapy (Rt) decreased ER overall from 27% to 13% and for elevated posttherapy ESR patients from 54% to 25%. When chemotherapy (Ct) was used as either adjuvant or initial therapy, ER were greatly reduced vs. Rt alone [overall (6% vs. 28%) and for patients with elevated posttherapy ESR (10% vs. 39%)]. Stepwise logistic regression showed Ct to be the most important factor "protecting" from EN relapse, but elevated posttherapy ESR was still significant. For early TDN relapse, elevated posttherapy ESR had the highest predictive value for relapse, greater than the types of radiation fields used and chemotherapy. An unexplained elevated posttherapy ESR, regardless of previous therapy, predicts for ER from aggressive HD, frequently in EN and irradiated areas, and warrants further early therapy.

Adult↗
PubMed1991

In situ testing of CO2 laser on dental pulp function: effects on microcirculation.

The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304-1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.

Animals↗
PubMed1991

Refeeding of infants with acute diarrheal disease.

The purpose of this study was to determine which infant formula among five would be the most efficacious for the refeeding of infants during an acute episode of diarrhea. Fifty male infants less than 12 months of age with severe diarrhea and at least 5% dehydration were admitted to a metabolic unit and studied in a prospective, single-blind protocol. Ten infants randomly received one of five types of formula: two-thirds diluted cow milk, cow milk formula (Nanon, Nestle, Inc., São Paulo, Brazil), Portagen, Pregestimil, or Prosobee (Mead Johnson & Co. Division, Evansville, Ind.). They continued to receive the same formula for 72 hours unless dehydration occurred. There were no associated infections, and they received no prior antibiotic treatment. Oral hydration together with intravenous fluid therapy was given to all patients during the initial treatment. During the first 72 hours of refeeding, patients fed Portagen excreted the least amount of stool and required reduced quantities of intravenous fluids or oral hydration. In contrast, patients fed diluted cow milk or any other formula had more severe diarrhea. Nine of the 10 patients fed Portagen completed the 72-hour treatment, whereas only 2 of 10 fed diluted cow milk tolerated it. Similarly, the cumulative proportions for high purging rate, dehydration, carbohydrate intolerance, and vomiting were more favorable for Portagen and least acceptable for diluted cow milk. No differences were found among the remaining three formulas tested. These data show that diluted cow milk is poorly tolerated by infants with severe diarrhea, whereas Portagen is more effective.

Acute Disease↗