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Biomedical subjects

S Baker

Publications and source records attributed to S Baker.

At least 163 records · Page 9Linked to original sources
PubMed1989

Visual and phonological components of working memory in children.

Previous studies have shown that young children's immediate memory for a short series of drawings of objects is mediated by a visual component of working memory, whereas older children rely chiefly upon a phonological component. Three experiments investigated the hypothesis that older children rely also, but to a lesser extent, on visual working memory. Experiment 1 confirmed previous evidence that 11-year-olds' memory is disrupted by phonemic similarity of object names, but is unaffected by visual similarity of the objects themselves. However, when articulatory suppression was used to prevent phonological coding, levels of recall were sensitive to visual rather than phonemic similarity. Experiment 2 compared the effects of interpolating an auditory-verbal or a visual postlist task on memory for drawings viewed either with or without suppression. The visual task had a clear disruptive effect only in the suppression condition, where it interfered selectively with recall of the most recent item. Experiment 3 compared the effects of interpolating an auditory-verbal or a mixed-modality (visual-auditory) postlist task when subjects were not required to suppress. There was greater interference from the mixed-modality task, and this effect was confined to the last item presented. These experiments are taken as confirming the presence of a small but reliable contribution from visual memory in 11-year-old children's recall. As in younger children, visual working memory in 11-year-olds is sensitive to visual similarity and is responsible for a final-item visual recency effect. The results also show that older children's use of visual working memory is usually masked by the more pervasive phonological component of recall. Some implications for the structure of working memory and its development are discussed.

Child↗
PubMed1989

Prognostic and therapeutic observations of manifestations in the genitourinary tract of adenocarcinoma of the colon and rectum.

To evaluate the significance of involvement of the genitourinary tract in adenocarcinoma of the colon and rectum, we received the records of 178 patients with adenocarcinoma of the colon and rectum admitted to the University of Massachusetts Medical Center from 1980 to 1985. Sixty-eight patients (38 per cent) had urologic manifestations categorized as ureteral obstruction or injury (34 per cent), invasion to the bladder or prostate, or both (10 per cent), isolated gross hematuria (18 per cent), radiation cystitis (6 per cent) and neurogenic bladder (26 per cent). Involvement of the genitourinary tract was more common among patients with recurrent versus primary carcinoma (53 versus 32 per cent) and among patients with high stage (Dukes' C and D) versus low stage (Dukes' A and B) carcinoma (48 versus 21 per cent). The survival rate was worse in patients with high stage compared with low stage disease and no patient with recurrent high stage disease survived beyond three years. Short term survival (less than two years) was not statistically different among patients with or without manifestations in the genitourinary tract: 63 and 45 versus 71 and 66 per cent at one and two years, respectively; however, the five year survival rate was worse among patients with genitourinary involvement (30 versus 54 per cent, p less than 0.05). Surgical and endoscopic intervention of the urinary tract was performed upon 36 patients with Dukes' C and D carcinoma because of life-threatening sepsis or azotemia, or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1989

Risk of fractures in an intermediate care facility for persons with mental retardation.

The epidemiology of fractures among 553 residents of an intermediate care facility for persons with mental retardation was examined. In a 10-month period, 61 fractures occurred among 55 residents; application of fracture rates in the United States revealed an expected number of 15 fractures among the 553 residents, p less than .001. Although 52% of fractures involved small bones of the hands and feet, elderly residents were more likely to fracture major bones and to suffer their fractures from a fall than were younger residents. The relationship between potential risk factors and fracture risk were examined and implications for preventive and rehabilitative measures discussed.

Accidental Falls↗
PubMed1988

Drosophila S virus, a hereditary reolike virus, probable agent of the morphological S character in Drosophila simulans.

Isometric reolike virions were found in all the examined Drosophila simulans flies from two strains (SimES-st and Israel-st) presenting the S phenotype, a maternally inherited morphological trait (abnormalities of bristles). Normal flies of both strains appeared virus-free. Virions were found in the cytoplasm of male and female gonads and epidermal cells, including the bristle-forming cells, which appeared disorganized. Steps of virogenesis were described. A positive correlation was demonstrated between expressivity of the S phenotype and degree of viral infection. This hereditary reolike virus seems to be responsible for the S character of D. simulans and was named DSV (Drosophila S virus).

Animals↗
PubMed1988

The release of residual monomeric methyl methacrylate from acrylic appliances in the human mouth: an assay for monomer in saliva.

A gas-liquid chromatography assay has been developed for the estimation of methyl methacrylate monomer (MMA) in whole saliva, with a lower limit of detection in the order of 1 microgram/mL. Healthy human dentate subjects wore recently made autopolymerized or heat-polymerized polymethyl methacrylate (PMMA) palatal appliances. MMA released into saliva was detected for up to one week after insertion of autopolymerized appliances, with a maximum concentration of 45 micrograms/mL in whole saliva or 180 micrograms/mL in the salivary film on the fitting surface. The MMA was not detected in blood or urine. MMA was also present in the saliva of volunteers wearing appliances which had been heat-polymerized at 70 degrees C for one hr but not cured at 70 degrees C for three hr. The maximum amount of monomer released by an autopolymerized base plate was 29.5 micrograms in the first hour, which, while not a toxic or primary irritant dose, could possibly sensitize patients or elicit an allergic reaction. For minimization of monomer release, autopolymerized appliances should be immersed for 24 hr in water before being worn.

Acrylic Resins↗
PubMed1988

Human immunodeficiency virus isolation studies and antibody testing. Household contacts and sexual partners of persons with hemophilia.

Virus isolation studies and human immunodeficiency virus (HIV) antibody testing were performed on 87 household contacts of 68 HIV antibody-positive hemophilic patients to determine the extent that HIV could be transmitted through heterosexual or through nonsexual, but intimate contact. Human immunodeficiency virus seropositivity was established for the 68 hemophiliacs by immunofluorescence method or enzyme-linked immunosorbent assay and confirmed by Western blot testing (for 66 patients). Fifty-one nonsexual contacts and 36 sexual partners of these hemophiliacs were tested for HIV antibody by immunofluorescence or enzyme-linked immunosorbent assay and Western blot. All sexual partners and all nonsexual household contacts were HIV antibody-negative, including six partners and nine parents of hemophiliacs from whom the virus had been isolated and seven parents and six partners of patients with AIDS. This study further demonstrates lack of transmission of HIV in intimate, but nonsexual settings, and suggests that heterosexual transmission, although well known to occur, may be relatively uncommon in hemophilic couples when the male and female partner have no other risk factors. It is hoped that intensive education and counseling programs will reduce exposure and maintain a low risk of heterosexual transmission.

Acquired Immunodeficiency Syndrome↗
PubMed1987

The effects of low-protein diet and testosterone on sex hormone-binding globulin capacity in male rabbits.

The effects of a low-protein high-carbohydrate (LPHC) diet (8% protein 65% to 72% carbohydrate) were compared to those of regular rabbit chow (14% to 16% protein 57% to 64% carbohydrate) on sex hormone-binding globulin (SHBG) capacity in 12 male rabbits. The six rabbits who were fed the LPHC diet for 8 weeks showed a significant increase in their mean SHBG capacity (mean +/- SE: from 70 +/- 16 nmol/L to 332 +/- 45 nmol/L, P less than .01) whereas the six rabbits fed the standard diet showed a slight decrease (from 106 +/- 22 nmol/L to 76 +/- 20 nmol/L, NS). These changes in SHBG capacity were mirrored by a decrease in percent-free T (from 2.64 +/- 0.26% to 1.64 +/- 0.16%, P less than .01) in the LPHC diet group and no change in percent-free T in the regular diet group (from 2.36 +/- 0.21% to 2.19 +/- 0.10%). The changes in SHBG capacity and percent-free T were not associated with significant changes in testosterone (T), free T, estradiol (E2), thyroxine, triiodothyronine, thyroxine-binding globulin, or cortisol binding globulin levels. In a subsequent experiment, testosterone cyclopentyl propionate (TCP) was administered to six male rabbits while on regular rabbit chow and again after 6 weeks of the LPHC diet. TCP administration did not cause any significant change in the SHBG capacity, but the LPHC resulted again in a significant (P less than .05) increase in SHBG capacity from 80 +/- 18 nmol/L. to 198 +/- 22 nmol/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Adult onset diabetes mellitus: glycemic control and family function.

To test the hypothesis that family function differs in patients according to their level of diabetes control, family function was assessed using the Family APGAR questionnaire in low-income patients with adult-onset diabetes who were under comprehensive care in five community health centers. From 3,000 active patients, a group of 385 with the following characteristics were randomly selected: mean age, 59.1 (range 25-93); M:F ratio, 1:4; and ethnic distribution (blacks: Hispanics: whites, 48%:31%:21%). Categorizing patients by their extent of diabetes control, good family function was found in 92% of patients in good control of their diabetes mellitus, in 66% of those in fair control, and only in 50% of those in poor control (p less than 0.005, chi 2 = 44.1, df = 2). Since these data point to the association between levels of family functioning and control of diabetes, further studies are needed to ascertain if an improvement in family functioning will lead to better diabetic control.

Adult↗
PubMed1987

Predictive value of the stomach wall pH for complications after cardiac operations: comparison with other monitoring.

The ability to predict impending complications after elective cardiac operations from measurements of BP, cardiac index, arterial pH, and urine output on the day of operation was compared with that of indirect measurement of stomach wall pH in 85 patients. We found that acidosis in the stomach wall was the most sensitive predictor for complications. The specificity of this predictive test increased exponentially as the duration and degree of intramural acidosis increased. Hypotension, acidosis, and oliguria, but not cardiac index, also predicted postsurgical problems. Stepwise logistic regression analysis of the data that showed postoperative complications were best predicted by the duration of hypotension, and the predictive ability was significantly improved when the duration of intramural acidosis was included.

Aged↗
PubMed1987

Hormones and handedness: left-hand bias in female congenital adrenal hyperplasia patients.

An excess of left-handers among males has been attributed to early androgen exposure. This theory was supported by our observation that girls with congenital adrenal hyperplasia (CAH) are more left-biased than their normal sisters. Male CAH patients, with prenatal androgen exposure similar to that of unaffected brothers, had typical male-handedness patterns.

Adolescent↗
PubMed1987

Immunologic aberrations, HIV seropositivity and seroconversion rates in patients with hemophilia B.

Because there have been reports that factor IX concentrate is less immunosuppressive and therefore factor IX users have less immunologic aberrations, we have studied a group of 22 patients with hemophilia B and six patients with factor VIII deficiency and high titer inhibitors with respect to lymphocyte numbers and function, human immunodeficiency virus (HIV) serology, and factor usage. This group was compared to 111 patients with hemophilia A and a group of 28 healthy male volunteer controls. When the study began in 1983, the majority of patients with hemophilia B and with higher titer factor VIII inhibitors were seronegative, 77% and 83% respectively, as compared to only 30% of patients with hemophilia A. At that time the factor IX users also had milder immune aberrations than the hemophilia A group. However, with time and increasing clotting factor concentrate usage, seroconversion and more striking abnormalities in immune function have occurred in the hemophilia B group. In a subgroup of 16 patients with hemophilia B studied twice, the incidence of seropositivity increased from 31% in 1983 to 69% in 1985. We thus conclude that factor IX concentrate in itself is not less immunosuppressive than factor VIII concentrate. Seroconversion in factor IX concentrate users appears to be lagging behind seroconversion in factor VIII concentrate users, perhaps secondary to the lower cumulative dosage of concentrate that patients with hemophilia B utilize.

Adolescent↗
PubMed1986

Inter-relatedness of some isoenzymes of cytochrome P-450 from rat, rabbit and human, determined with monoclonal antibodies.

Monoclonal antibodies have been raised to rat liver cytochromes P-450 b and c, and rabbit liver cytochrome P-450 form 4. A total of six antibodies have been studied. Each antibody reacted strongly both with its homologous antigen and with microsomal fractions selectively enriched with that antigen by treatment of animals with inducing compounds. However, several of the antibodies showed cross-reactivity, either within or between species. A combination of enzyme-linked immunosorbent assay, immunoadsorption, Western blotting and competitive radioimmunoassay revealed that each of the antibodies reacted with a different epitope. Proteolytic digestion of antigen followed by Western blotting of the peptide fragments enabled antibodies, otherwise identical in their reactivity, to be distinguished. It is concluded that complex structural relationships exist amongst the different isoenzymes of cytochrome P-450 and that epitope mapping will help in characterizing both animal and human cytochromes P-450.

Animals↗
PubMed1986

Amiodarone for refractory atrial fibrillation.

Atrial fibrillation (AF) is a difficult arrhythmia to manage with antiarrhythmic agents. Amiodarone is highly effective in restoring and maintaining normal sinus rhythm in patients with AF. However, the mechanism and predictors of efficacy for amiodarone in treating AF have not been adequately addressed. Various measures of success or failure of amiodarone therapy were examined in 68 patients who had paroxysmal or chronic, established AF refractory to conventional antiarrhythmic agents. The patients were 25 to 75 years old (mean 59) and mean follow-up was 21 months (range 3 to 56). Maintenance amiodarone dosages were 200 to 400 mg/day. Overall, amiodarone therapy was effective long term in 54 of the 68 patients (79%). Left atrial diameter, age, gender and origin of AF were not helpful in predicting success or failure of amiodarone therapy. The presence of chronic AF for longer than 1 year was an adverse factor in maintaining normal sinus rhythm (p = 0.007), although the success rate even in this group was relatively high (57%). Thirty-five percent of the patients had adverse effects, which precluded long-term therapy with amiodarone in 10%.

Adult↗
PubMed1986

Prediction of the development of sigmoid ischemia on the day of aortic operations. Indirect measurements of intramural pH in the colon.

A deviation in an indirect measurement of intramural pH below the limits of normality (6.86) was used as a diagnostic test for sigmoid ischemia in 25 high-risk patients undergoing abdominal aortic operations. The clinical diagnosis of ischemic colitis was made by the attending physicians in only two of the 25, on the day after operation in one and three months after operation in another. In neither was the ischemic colitis considered to have been a causative factor in their subsequent deaths. In contrast, six patients developed pH evidence of ischemia on the day of operation. All six subsequently developed a transient episode of guaiac-positive diarrhea, four developed physical signs consistent with ischemic colitis, and four died. Of 19 who did not develop pH evidence of ischemia, none developed guaiac-positive diarrhea, none developed any signs of ischemic colitis, and none died. Stepwise logistic regression showed the duration of pH evidence of ischemia on the day of operation to be the best predictor for the symptoms and signs of ischemic colitis and for death after operation.

Aged↗
PubMed1986

Gastric antisecretory and antiulcer properties of enprostil, (+/-)-11 alpha, 15 alpha-dihydroxy-16-phenoxy-17,18,19,20-tetranor-9-oxoprosta- 4,5,13(t)-trienoic acid methyl ester.

Prostaglandins of the E series have been shown, both in animals and humans to produce gastrointestinal antisecretory and antiulcer effects. Enprostil, a modified allenic prostaglandin E was found to be a highly potent inhibitor of gastric HCl secretion in a variety of species. In rats, in which both the pylorus and esophagus were ligated, p.o. ED50 values and 95% CL for inhibiting acid secretion evoked by histamine, pentagastrin and carbachol were 9.9 (6.7-15), 40 (11-145) and 0.83 (0.78-0.89) micrograms/kg, respectively. In inhibiting histamine-evoked acid secretion, enprostil was more potent when administered p.o. than when injected into the duodenum or s.c. When enprostil was injected directly into the pouch of Heidenhein dogs, intense antisecretory activity occurred, ED50 = 0.9 (0.7-1.1) micrograms/kg, whereas, when given p.o. to the main stomach the ED50 was 6.6 (3.2-13.6) micrograms/kg. Administration of cimetidine either p.o. or to the pouch resulted in virtually identical ED50 values, viz., 2.9 and 3.1 mg/kg. Enprostil also inhibited dimaprit- and pentagastrin-induced acid secretion in cats with permanent gastric fistulae. The oral ED50 values for inhibiting acid secretion evoked by these two secretagogues were 2.5 (1.4-4.3) and 0.8 (0.5-1.5) micrograms/kg, respectively. Enprostil was extremely potent in preventing indomethacin plus "cold stress" ulcers in rats. When given orally the ED50 was 0.61 (0.31-1.22) and s.c. it was 22 (9.0-52) micrograms/kg. It was also highly potent in preventing cysteamine-induced duodenal ulcers when given p.o., ED50 = 20 (17-23) micrograms/kg. Thus, enprostil is a highly potent antisecretory and antiulcer agent. It appears to act topically; directly at gastric mucosal sites.

Animals↗
PubMed1986

False-negative peritoneal cytology in metastatic ovarian carcinoma.

Seventy-nine laparotomies for disseminated intraperitoneal ovarian carcinoma were reviewed to determine the frequency and possible causes of false-negative peritoneal cytology. Negative peritoneal cytology (defined as any reading other than positive) was found in 16 of 79 cases (20%). False-negative cytology occurred more frequently with peritoneal washings (48%) than with ascites (6%; P less than .001); with second-look surgery (50%) than at primary surgery (12%; P = .004); with peritoneal metastasis less than 0.5 cm (50%) than with metastasis greater than 0.5 cm (16%; P = .02); and with bloody cytology specimens (25%) rather than specimens without blood (0%; P = .06). Volume of peritoneal specimen, architectural grade, cytologic grade, and stage of disease (III versus IV), did not affect the frequency of false-negative cytology. The high prevalence of negative cytology associated with peritoneal washings, small tumor size, and second-look surgery suggests that negative cytology is a result of poor distribution of peritoneal washings and infrequent exfoliation of malignant cells rather than misinterpretation of malignant cells present in cytology specimens.

Ascitic Fluid↗