Search PubMed⌕ Search

Biomedical subjects

R D Johnson

Publications and source records attributed to R D Johnson.

At least 199 records · Page 11Linked to original sources
PubMed1978

Further characterization of Mycobacterium ulcerans toxin.

Mycobacterium ulcerans produces an exotoxin in culture which, when inoculated into guinea pig skin, causes inflammation, necrosis, edema, and other histopathological changes resembling those in infections of humans. The toxin was resistant to heat and to alkalies and was moderately acid labile. Toxic activity was destroyed by Pronase, phospholipase, lipase, amylase, and glucosidase but not by trypsin, collagenase, cellulase, lysozyme, hyaluronidase, or neuraminidase. Toxic activity was resistant to treatment with 2-mercaptoethanol, urea, guanidine hydrochloride, p-chloromercuribenzoate, ethylenediaminetetraacetate, and sodium deoxycholate but was destroyed by sodium m-periodate and sodium dodecyl sulfate. The toxin was precipitated by a wide range of ammonium sulfate concentrations. Extraction with chlorofrom-methanol or petroleum ether destroyed its activity. Isopycnic density gradient ultracentrifugation in KBr produced a high-density lipoprotein layer with a 24-fold increase in specific activity. The results indicate that this toxin is a high-molecular-weight phospholipoprotein-polysaccharide complex.

Centrifugation, Density Gradient↗
PubMed1978

The chest radiograph in legionnaires' disease.

The chest radiographs of 24 patients with documented Legionnaires' disease were evaluated. Twenty-two of the 24 patients had positive findings for the disease initially. There was unilateral involvement in 68% and the most common lung shadows were poorly marginated round opacities (46%), diffuse patchy (25%) and peripheral opacities (21%). At peak, 70% of patients had a lobar shadow. Pleural effusions were present in 39% of cases but could be explained by underlying congestive heart failure or renal failure in 7 of the 9. Although the findings are not specific, the radiologist should consider this diagnosis in a patient with compatible clinical history, a pneumonia of obscure etiology, and these radiographic manifestations.

Adolescent↗
PubMed1977

Carcinoma of the endometrium: radiation followed immediately by operation.

A prospective study was established in August, 1967, to treat all adenocarcinomas of the endometrium by protocols of preoperative radiation followed immediately by operation. Two hundred and ninety-five women have been treated, 220 of whom had Stage I disease. In these cases, factors known to be associated with survival were studied, and their influence upon survival was noted. Preoperative radium followed immediately by operation was the primary method of therapy. Life tables demonstrated a five-year survival rate of 91 per cent with a low complication rate in patients with Stage I disease. Cell type, degree of differentiation, and depth of myomentrial invasion were the primary factors influencing survival.

Adenocarcinoma↗
PubMed1977

Pesticide and other chemical residues in total diet samples (XI).

In the Total Diet study, the Food and Drug Administration has, since 1964, reported residues of pesticides and other chemicals ingested in the average diet of the Nation's largest eater, the young adult male. During the eleventh year of the study, pesticide residues remained at the relatively low levels reported previously. Twenty market baskets were collected in 20 cities which ranged in population from less than 50,000 to 1,000,000 or more. Averages and ranges of residues found are reported for August 1974 through July 1975 by food class. The individual items used in making up the dairy and meat composites in four market baskets were analyzed for pesticides and the results are included. Data for lead, cadmium, selenium, mercury, arsenic, and zinc are also included. Results of recovery studies within various classes of residues are also presented.

Diet↗
PubMed1977

Pesticide and other chemical residues in total diet samples (X).

Since 1964 the Food and Drug Administration Total Diet study has reported residues of pesticides and other chemicals ingested in the diet of a young adult male, statisically the Nation's largest eater. During the tenth year of the study, pesticide residues remained at the relatively low levels previously reported. Thirty market baskets were collected in 30 cites which ranged in population from less than 50,000 to 1,000,000 or more. Averages and ranges of residues are reported from August 1973 through July 1974 by food class. Individual items in the dairy and meat composites in four market baskets were analyzed for pesticides; results are included. Data for lead, cadmium, selenium, mercury, arsenic, and zinc are also included. Results of recovery studies within various classes of residues are also presented.

Beverages↗
PubMed1976

In vivo assessment of decarboxylase inhibition or potentiation: urinary dopamine and L-dopa output after L-dopa administration.

In the L-Dopa treated rat, a decreased urinary output of free and conjugated dopamine and an increase in free and conjugated L-Dopa excretion after administration of decarboxylase-inhibiting drugs provide a good in vivo index of Dopa decarboxylase inhibition. With the exception of free dopamine output, which showed an equivocal change, these measurements appear to provide a good yardstick of decarboxylase status in man also. Using this approach, it was not possible to find any evidence of facilitation of decarboxylase action, in L-Dopa-treated parkinsonians given pyridoxine supplements, to account for the ability of this compound to neutralize the beneficial effect of L-Dopa.

Animals↗
PubMed1976

A senior-year experience similar to an internship.

A senior year experience similar to an internship was initiated in community hospitals. It is designed to shorten the overall length of training and to restore a broad-based clinical experience to the period of "intermediate patient care responsibility" in the training of new physicians. The program provides students with an opportunity to observe and practice in a primary care setting and expands the clinical resources of the medical school. Analysis of the performance of students in the class of 1974 indicates that they perform on a level comparable with first-year house officers. This program provides a general clinical experience for those students who have not yet decided on future training plans or who are going into primary care fields.

Clinical Competence↗
PubMed1976

Pesticide residues in total diet samples (IX).

During the ninth year of the Total Diet Study, pesticide residues remained at the relatively low levels reported previously. Thirty market baskets were collected in 30 cities which ranged in population from less than 50,000 to 1,000,000 or more. Averages and ranges of residues found are reported for the period August 1972 through July 1973 by food class. Lead, selenium, and zinc data are included for the first time. During this period, the individual items used in making up the dairy and meat composites in four market baskets were analyzed for pesticides and the results are included. Results of recovery studies within various classes of residues are also presented.

Animals↗
PubMed1975

Spinal cord regeneration in rats after immunosuppressive treatment. Theoretic considerations and histologic results.

Some species of animals and some early developmental stages of other species are capable of central nervous system (CNS) regeneration. These species and developmental stages also have reduced or absent allergic reaction to tissue homografts. Mammals are allergic to their own brain antigens, and experimental allergic encephalomyellitis (EAE) can be produced when they are exposed to parenterally administered brain antigen. Immunosuppressive treatment will delay or prevent the production of EAE in rats. In our experiments, immunosuppressive treatment made possible the electrophysiologic study of regeneration of long descending motor tracts of the spinal cord in rats six months after spinal cord transection. Histologic evaluation showed no comparative difference in scar at the site of transection when treated animals were compared with controls. Neither was any difference noted between animals in which regeneration was shown electrophysiologically and those without such regeneration. Perhaps humoral antibodies play a role in the prevention of functional regeneration in the rat.

Animals↗
PubMed1975

Pesticide residues in total diet samples (VIII).

During the eighth year of the Total Diet Study, residues remained at the relatively low levels reported previously. A total of 35 market baskets were collected in 32 cities which ranged in population from less than 50,000 to 1,000,000 or more. Averages and ranges of residues found are reported for the period June 1971 through July 1972 by region and food class. Results of recovery studies within various classes of residues are also presented.

Beverages↗