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Biomedical subjects

D A Johnson

Publications and source records attributed to D A Johnson.

At least 361 records · Page 20Linked to original sources
PubMed1979

Complexes formed by (pyrimidine)n . (purine)n DNAs on lowering the pH are three-stranded.

(Pyrimidine)n . (purine)n DNAs of repeating sequences form a distinctive complex on lowering the pH below 6. Previously this complex was thought to be tetra-stranded. The present work is inconsistent with this view, and four lines of evidence show that the complex consists of a triplex together with a poly d(purine) possessing secondary structure. Formula: (see text). (a) S1 nuclease digestion leads to degradation of 50% of the poly d(purine) content of the pH 5-induced complex. (b) Buoyant density studies demonstrate that there is no interaction between the triplex and added free poly d(purine) and also that the complex formed from duplex DNA contained poly d(purine) which is free to form a triplex on addition of an appropriate poly d(pyrimidine) in the correct stoichiometry. (c) The hyperchromic shifts of the triplex and poly d(purine), upon melting, are mutually independent. (d) The circular dichroism spectrum of the complex is simply the weighted average of a triplex together with a free poly d(purine). The triplexes have tm's approximately 20 degrees higher than the corresponding duplexes under comparable conditions and they are extremely resistant to various deoxyribonucleases; properties which may prove useful for their isolation from natural sources.

Base Sequence↗
PubMed1979

Weight changes with depot neuroleptic maintenance therapy.

A prospective study of schizophrenic patients prescribed injectable depot neuroleptic drugs as maintenance therapy showed a clinically significant weight gain in 55% of patients. No significant difference was shown between flupenthixol decanoate and fluphenazine decanoate, nor was a clinically meaningful relationship shown with dose, or the use of anti-parkinsonian drugs. The weight gain continued for at least 2 years following a mental state relapse. It is suggested that the monitoring of weight and giving of appropriate advice on diet are two essential in maintenance therapy of chronic schizophrenia.

Body Weight↗
PubMed1979

A double-blind comparison of flupenthixol, nortriptyline and diazepam in neurotic depression.

A double-blind trial of flupenthixol, nortriptyline and diazepam in neurotic depression using flexible dose schedules suggested that each drug is an efficient treatment for this category of depression although the patterns of response and prevalence of side-effects varied. No differences reaching a level of significance could be shown on rating scales of depression or anxiety, but trends favoured flupenthixol. However, clinical evaluation suggested flupenthixol to be more effective than diazepam on mental state examination (P less than 0.05) and to have a greater overall therapeutic effect than nortriptyline (P less than 0.05). It also had fewer side-effects than nortriptyline (P less than 0.05).

Adjustment Disorders↗
PubMed1979

Risk factors associated with failure to receive vaccinations.

A major purpose of a state-wide survey to document the vaccination status of 1,003 2-year-old children was to identify factors associated with failure to receive the recommended vaccinations. With a basic series of immunization defined as three doses of diphtheria-tetanus-pertussis (DTP), three oral polio vaccine (OPV), one measles, and one rubella, 72.5% of the children had completed the series. When the completed series was redefined to include a fourth DTP and mumps vaccine the rate of completion dropped to 40.8%. However, 59.1% of the children who had not completed this optimal series could be brought up-to-date with a single visit to their provider of medical care. Demographic variables independently associated with completion of the basic series were increased paternal education (P less than .001), increased maternal education (P less than .02), smaller family size (P less than .01) and higher socioeconomic status, as determined by census tract or rural town of residence (P less than .02). Race was not found to be a factor associated with vaccination rates when socioeconomic status was controlled. Patients who received their vaccinations from private physicians had a better vaccination rate than those who attended health department clinics. This difference persisted even when socioeconomic status was controlled by residence (P less than .02). The simultaneous comparison of parental education and family size demonstrated that a child having one parent with less than 12 years education or having at least three siblings has a fourfold greater risk of failure to complete his immunization than children whose parents are both college graduates. By using paternal and maternal education level and family size as screening variables, children at high risk for failure to complete their immunizations could be identified prospectively and made the target of intervention programs to improve compliance.

Child↗
PubMed1978

Rabbit acrosin: immunological dissimilarity to rabbit trypsin (1).

Antibodies obtained from guinea pigs injected with rabbit pancreatic trypsin together with antibodies raised in rabbits against bovine acrosin or bovine pancreatic trypsin were reacted against various mammalian trypsins and acrosins in double diffusion tests. The results of immunodiffusion analyses reveal antigenic dissimilarity between rabbit acrosin and rabbit trypsin.

Acrosin↗
PubMed1978

Role of bacterial products in periodontitis: immune response in gnotobiotic rats monoinfected with Eikenella corrodens.

The development of humoral and cell-mediated immune responses to Eikenella corrodens (a bacterium that causes periodontal lesions in gnotobiotic rats) was measured and compared with the rate of appearance of macroscopic lesions. A possible inverse relationship was found. A strong cell-mediated immune response, as measured by skin reactivity and lymphocyte mitogenesis, occurred between 4 and 6 weeks after infection and subsided soon thereafter to a low response level. Humoral antibodies to endotoxin from E. corrodens could not be detected at any time. The disease developed only after the cell-mediated immune response diminished, thus suggesting that lack of an efficient immune response may permit the development of the disease. This is seemingly in contradiction to the assumption that tissue destruction in such cases is caused by the immune response and its products. We are inclined to believe, based on our findings reported here, that the lack of immune responsiveness to the bacterium and/or its products is the major causative factor in the development of periodontitis. At the same time, we wish to emphasize that occurrence of both phenomena during the long development of periodontal disease is possible.

Animals↗
PubMed1978

Role of bacterial products in periodontitis: humoral immune response to Eikenella corrodens.

Eikenella corrodens can induce periodontitis-like disease in gnotobiotic rats. Some components of this bacterial cell elicit measurable humoral immune response during the development of the disease, but in this system endotoxin is not among the efficient immunogens. Because no humoral immune response could be seen to the endotoxin of Eikenella corrodens it is assumed that this endotoxin can act uncontrolled in monoinfected rats. Accordingly, the lack of protective humoral immune response to pathogenic components of Eikenella corrodens may be the major factor permitting the development of the disease described here. The possibility that both cell-mediated immunity and uncontrolled endotoxic action are parts of the pathomechanism of the disease is supported by our observations.

Animals↗
PubMed1978

NMR studies of sustained release methadone tablets.

NMR studies for the identification of methadone in sustained release tablets is conducted. Up-field shifts of the N-methyl and phenyl groups of the compound were observed. These changes indicate an increased lipid solubility and therefore better absorptivity of the drug in the current form.

Delayed-Action Preparations↗