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Biomedical subjects

D A Sack

Publications and source records attributed to D A Sack.

194 records · Page 11Linked to original sources
PubMed1976

Neuroelectric blocking factors in human and animal sera evaluated using the isolated frog spinal cord.

The effects of sera from guinea-pigs with experimental allergic encephalomyelitis (EAE) and multiple sclerosis (MS) patients were evaluated and compared with the activity of control sera using the isolated frog spinal cord. Ventral root responses (VRR) were recorded during supramaximal ipsilateral dorsal root stimulation in the presence and absence of 25% serum. In control experiments with normal human and guinea-pig sera we observed a consistent, reversible increase in VRR averaging 20% and 17% respectively, and in no case was any significant decrease produced. In contrast, sera from EAE guinea-pigs 12 to 19 days after injection produced an equally rapid, reversible decrease in VRR. The decrease averaged 36% and was highly significant (P less than 0.0001) relative to controls. Similarly, sera from MS patients on the average decreased the VRR by 26%, and this again was significant compared with controls (P less than 10(-6).

Animals↗
PubMed1975

Diarrhoea associated with heat-stable enterotoxin-producing strains of Escherichia coli.

Five patients who developed acute watery diarrhoea while travelling in Mexico in October, 1974, were found to have enterotoxigenic Escherichia coli in their stool which produced heat-stable enterotoxin (S.T.) without producing heat-labile enterotoxin (L.T.). These S.T.-only E. coli, which have previously been described as causing diseases in animals, must now be regarded as pathogenic for humans as well.

Adult↗
PubMed1975

Enterotoxigenic Escherichia-coli-associated diarrheal disease in Apache children.

A search for intestinal enterotoxigenic Escherichia coli was made in 59 Apache children hospitalized with 64 episodes of acute diarrhea. Esch. coli isolates from acute-phase and convalescent-phase specimens of small-bowel fluid and stool were tested in three currently recognized models: the adult-rabbit ileal loop; infant rabbit; and the adrenal-cell assay. Enterotoxigenic strains were isolated from 10 children during acute diarrheal episodes (16 per cent); none were isolated from convalescent-phase specimens. None of 64 "enteropathogenic" serotypes of Esch. coli from 43 children with diarrhea, however, caused fluid production in the ileal-loop model. These results suggest that enterotoxigenic Esch. coli may be the cause of considerable diarrhea in this population and that the term "enteropathogenic" as applied to serotypes of Esch. coli needs to be redefined.

Acute Disease↗
PubMed1975

Test for enterotoxigenic Escherichia coli using Y-1 adrenal cells in miniculture.

A rapid, potentially clinically useful test for detection of enterotoxigenic Escherichia coli is described. Whole bacterial cultures of enterotoxigenic E. coli, when briefly exposed to Y1 adrenal cells in tissue miniculture, effect a rounding response in the tissue culture that can be discerned at 18 to 24 h. The tissue culture technique agreed with the rabbit ileal loop in all 58 enterotoxigenic and 52 non-enterotoxigenic E. coli strains tested.

Adrenal Glands↗
PubMed1975

Antibodies to heat-labile Escherichia coli enterotoxin in Apaches in Whiteriver, Arizona.

Antitoxin titers to heat-labile Escherichia coli enterotoxin were measured in Apache children hospitalized with acute diarrhea and in Apaches of different age groups without diarrhea in Whiteriver, Ariz. The study suggests that in this locale, exposure to enterotocigenic E. coli is probably widespread and occurs early in life. Antitoxin titer rises after idarrheal disease associated with enterotocigenic E. coli infection, however, were not regulary found.

Antitoxins↗
PubMedDate not supplied

Acute lower respiratory tract infections in hospitalized patients with diarrhea in Dhaka, Bangladesh.

This study focused on 401 children less than 5 years old who were hospitalized with acute lower respiratory tract infection (ALRI) and diarrhea in Dhaka, Bangladesh, and who were investigated for the presence of both bacterial and viral respiratory tract pathogens as well as for selected diarrheal pathogens. The most common manifestations of ALRI were pneumonia (374 cases), bronchiolitis (12 cases), and tracheobronchitis (11 cases). The majority (77%) of the illnesses were in children less than 2 years of age, and 88% of the children were malnourished. A respiratory tract pathogen was identified in 30% of the patients, and a diarrheal pathogen was identified in 34%. The overall case-fatality rate in children with ALRI and diarrhea was 8%. The case-fatality rate was 14% in children with bacterial pneumonia and diarrhea, 3% in those with viral pneumonia and diarrhea, and 14% in malnourished children with shigellosis and ALRI. The most common respiratory tract pathogens were respiratory syncytial virus, Streptococcus pneumoniae, influenza viruses, and Haemophilus influenzae type b.

Acute Disease↗
PubMedDate not supplied

Acute lower respiratory tract infection due to virus among hospitalized children in Dhaka, Bangladesh.

The nature of acute lower respiratory tract infection (ALRI) in hospitalized children and of the associated viral agents was assessed in a study of 601 children less than 5 years old over a 24-month period. Of these children, 80% were less than 24 months of age and the ratio of boys to girls was 1.7:1. Pneumonia (86.5% of cases) was the most frequently observed clinical manifestation. Shedding of virus was detected in 21.1% of the children; the highest rate occurred in infants 0-5 months old (27%) as compared with a rate of only 12.5% in children 25-60 months old. Virus was detected in 33.3%, 32.8%, 21.2%, and 20% of the cases of tracheobronchitis, bronchiolitis, pneumonia, and croup, respectively. Among the viruses detected, 78% were respiratory syncytial virus (RSV) (91% of infections with this virus occurred in children less than 2 years old) and 14.4% were influenza virus types A and B. Of the RSV infections, 61% occurred in infants less than 1 year old. The case-fatality rate was 6.8% overall and was 4.8% in virus-associated cases. No consistent pattern of seasonal occurrence of viral infections was discerned. RSV was detected throughout the year, with increased prevalence from January to April.

Acute Disease↗
PubMedDate not supplied

Highly symptom-aware children were heavily infected with urinary schistosomiasis in southern Ghana.

OBJECTIVES: To assess the relationship between the infection status of children and their knowledge, attitudes, beliefs, and practices (KABP) related to urinary schistosomiasis. DESIGN: Questionnaire survey. SETTING: Nine schools in eight rural communities (total population: 4,636) in Ga and South Akuapem Districts, Ghana. SUBJECTS: Four hundred and six children attending primary and secondary schools. MAIN OUTCOME MEASURE: Schistosoma haematobium infection status of children and their KABP. RESULTS: Of 354 children who responded and also submitted their urine samples, 297 (83.9%) tested positive for S. haematobium and the intensity of infection was 90 (95% CI: 74 to 110) eggs per 10 ml urine. General knowledge variables such as the knowledge of symptoms (p < 0.001), and knowledge of swimming or bathing in the river as a transmission route (p < 0.001) showed significant association for higher prevalence and intensity of infection. Treatment-seeking behaviour was not associated with the lower prevalence or intensity of infection. Practice variables such as washing clothes in the stream (p < 0.001) and fishing in the stream (p < 0.01) were significantly associated with both higher prevalence and higher intensity of infection. Children who knew of contact with river water as a transmission route reported more water contact activities (p < 0.001). CONCLUSION: This study showed that highly symptom-aware people were heavily infected, and people frequently exposed to infested water were heavily infected. Moreover, highly symptom-aware people never constituted a group whose exposure was slight. Why was awareness of disease symptoms and general knowledge of the disease not linked to low infectivity? Why didn't awareness result in avoidance of infested water sources? This report highlights the urgent need to address these important questions in future research.

Adolescent↗
PubMedDate not supplied

Plasmid profile as a useful marker of a Shigella dysenteriae type 1 strain causing an epidemic of shigellosis.

Plasmid profiles of 60 Shigella dysenteriae type 1 isolates obtained during an epidemic period (April - October 1983) were compared with that of 74 other Shigella species isolated during the same period of time and also with that of 20 S. dysenteriae type 1 isolates obtained before the epidemic period (1969 - 1982). All samples were collected during an epidemic of shigellosis from diarrhoeal patients being treated at the Dhaka Treatment Centre of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) between April and October 1983. Approximately 4% of the patients were sampled. The isolated showed varied patterns of resistance to several antimicrobial agents. Ninety-two per cent of the 60 S. dysenteriae type 1 strains showed a typical profile of four plasmids with masses of 140, 6, 4 and 2 megadaltons (Mdal). The finding is in contrast with that of a previous study at the ICDDR,B, in which 14 different plasmid profiles were observed in 23 strains of S. dysenteriae type 1 isolated during a 10 - month period in 1982. The profile typical for this study was different from those found in other species of Shigella isolated at the same time. There was a strong association between the possession of this plasmid profile and resistance to chloramphenicol, streptomycin, tetracycline and trimethoprim - sulphamethoxazole. Twenty S. dysenterae type 1 strains isolated from the faeces of patients at the ICDDR,B during 1969 - 1982 were also analysed for their plasmid profiles. The finding is in contrast with that of the epidemic strains. The typical epidemic plasmid pattern, i.e. the 140, 6, 4 and 2 Mdal, was absent in isolates obtained before 1983 epidemic.(ABSTRACT TRUNCATED AT 250 WORDS)

Bangladesh↗
PubMedDate not supplied

Enteropathogenicity of plesiomonas shigelloides by oral inoculation in adult conditioned rabbits.

To study presumptive diarrhoeagenic and invasive properties of Plesiomonas shigelloides, adult conditioned rabbits (n = 75) were fed 10(10) CFU of 3 isolates (2 from diarrhoea patients and one from river water) of the organism, and one isolate of Shigella sonnei (from a dysentery patient as positive control) or brain-heart infusion broth (as negative control). Each rabbit received in succession i.v. cimetidine (50 mg/kg body weight), two 15 ml oral doses of 5% NaHCO3 at 15 and 30 minutes respectively, prompt bacterial or sham inoculum followed 30 minutes by 2 ml of i.p. tincture of opium. Rabbits fed with P. shigelloides did not die or develop diarrhoea, but in a majority of them, histopathological examinations of the intestine revealed mild acute inflammation of the mucosa, mainly in the ileum. There was no serum antibody response by indirect haemagglutination against the lipopolysaccharide of the homologous strains of P. shigelloides. The culture filtrates of the organism also did not show any cytotoxic morphological changes on CHO and Y1 adrenal cell cultures. By contrast, rabbits fed with S. sonnei developed clinical diarrhoea, small to widespread severe acute inflammation of the gut mucosa, and all died on day 7. It may be concluded that P. shigelloides are able to provoke a mild inflammatory lesions of the gut mucosa in this rabbit model; but there is little prospect of using this model to assess easily the virulence of the organism.

Animals↗
PubMedDate not supplied

Antidepressant effects of sleep deprivation and phototherapy.

In contrast to drugs, sleep deprivation and phototherapy rapidly induce depressive remissions, which are rapidly reversible. These characteristics make them useful tools for prospective, longitudinal studies of the psychobiology of depression. It seems likely that discovery of the mechanism of action of these two antidepressant procedures would increase our understanding of the pathogenesis of depression and lead to novel, rapidly acting pharmacological treatments. Further progress in this direction depends on careful delineation of which conditions of the procedures are necessary for their antidepressant efficacy and identification and pharmacological manipulation of biological correlates of the procedures that may be relevant to their mechanism of action. Analogies between the two procedures suggest that similar mechanisms may be involved in both.

Atenolol↗