Biomedical subjects
Publications and source records attributed to C Liu.
A case of pneumococcal sepsis with DIC is reported. The patient had hyposplenism from thorium dioxide administration 23 years previously. Evidences of consumptive coagulopathy were verified by clinical manifestations of shock, generalized petechiae, abnormal hemostatic studies, and autopsy findings. The possible pathogenetic mechanism(s) of DIC in hyposplenism and pneumococcemia are reviewed.
Lysyl-transfer ribonucleic acid (tRNA) synthetase activity was compared in three independently isolated Escherichia coli K-12 mutants of the enzyme S-adenosyl-L-methionine synthetase (metK mutants) and their isogenic parents. In all three cases the activity of the lysyl-tRNA synthetase was elevated two- to fourfold in the mutant strains. Glycyl-L-leucine (3 mM) usually enhanced lysyl-tRNA synthetase activity two- to threefold in wild-type cells but did not further stimulate the synthetase activity in metK mutants. By two other criteria, the lysyl-tRNA synthetase from wild-type cells grown with the peptide and from the metK mutant RG62, grown in minimal medium, were similar. These criteria are enhanced resistance to thermal inactivation and altered susceptibility to endogenous proteases when compared with the synthetase from wild-type cells grown in minimal medium. In a separate set of experiments, the activities of the lysyl-, arginyl-, seryl-, and valyl-tRNA synthetases were measured in an isogenic pair of relt and rel strains of E. coli grown in a relatively poor growth medium (acetate) and in enriched medium. In the rel+ strain the level of all four synthetases was higher (two- to fourfold) in the enriched medium as expected. In the rel strain the difference in the activities of the synthetases between the two media were diminished. In all four cases the activities of the synthetases were higher in acetate medium in the rel strain. Evidence is presented that these two modes of metabolic regulation act independently.
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The authors observed prospectively 28 brain-injured patients, who required respiratory tract intubation, to determine the effect of antibiotic prophylaxis on bacterial flora, the rate of flora change, and the appearance of infection. Antibiotics not only failed to alter the rate of abnormal colonization but were associated with an earlier appearance of Gram-negative bacilli, the organisms that produced the most severe infections. Although more infections occurred in patients initially untreated with antibiotics, these infections were usually mild and caused by organisms susceptible to highly effective and relatively safe drugs. Although highly reproducible as a laboratory determination, the nitroblue tetrazolium dye test score showed no consistent relationship with the presence or absence of bacterial infection. Regular and extensive clinical and laboratory observations, including cultures of the respiratory tract helped to make the antibiotic administration in these patients specific, appropriate, and reasonable. Broad spectrum antibiotic prophylaxis does not prevent and may enhance the development of severe pulmonary infection in these patients.
The effect of aurodox on its own biosynthesis by Streptomyces goldiniensis was studied. It was found that addition of exogenous aurodox inhibits further accumulation of aurodox by the antibiotic-producing culture. Both long term fermentation studies with aurodox-14C and precursor incorporation studies over short time periods indicated that aurodox synthesis was regulated by feedback inhibition. The concentration of aurodox required to completely block further synthesis of the antibiotic was about 400 microng/ml. This is the same as the maximum concentration of aurodox normally accumulated by the culture used in this study. Antibiotic synthesis was inhibited not only by aurodox but also by some structural analogs of aurodox including several having no antibacterial activity. This effect was immediate and readily reversible, indicating that it could be due to inhibition of an enzyme(s) involved in the biosynthesis of aurodox.
Antibodies to Herpesvirus hominis (HVH) were evaluated by indirect immunofluorescent antibody (FA) method. Frozen sections of HVH infected mouse brain provided antigens for FA staining. Our data indicate that indirect FA staining is a rapid, sensitive, and reproducible method for measurement of antibodies to HVH. Indirect FA method can be applied as an additional tool for the measurement of antibodies to HVH and can be applied for epidemiological survey of HVH infections.
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Leg neuralgia is usually caused by nerve root irritation, and is seldom considered of viral origin. Two married couples had recurrent leg pain in a dermatome distribution. In each episode, after one to three days of neuralgia, herpetic vesicles appear on or near the genitalia. Herpesvirus hominis (HVH) was isolated from vesicles or cervix in three patients and was serologically identified as herpesvirus honinis type 2. Prolonged follow-up has not shown progression of the syndrome or any permanent neurologic damage. Treatment with topical neutral red and photoinactivation has not only reduced local lesion healing time and frequency of attacks, but it has also given prompt relief of neuralgia.
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Hepatotoxicity has been noted by several investigators during parenteral use of clindamycin, and some have reported that drug half-life is prolonged in the presence of liver disease. We administered 300 mg of clindamycin intravenously at 12-h intervals for 2 days to patients with acute and chronic hepatitis, cirrhosis, and controls to determine whether clindamycin will exacerbate preexisting hepatic dysfunction or whether drug excretion will be delayed in patients with liver disease as compared with controls. Exacerbation of hepatotoxicity was not found in this study. There was a small, but significant, delay in drug elimination between cirrhotics and controls, even after the first dose of clindamycin (P < 0.05); however, half-lives in all categories were in the range usually considered normal. We conclude that clindamycin can be used in liver disease in some circumstances, if proper precautions are exercised.
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Nephropathy, eosinophilia and fever were observed in an 18-year-old man being treated for staphylococcal septicemia. Parenteral challenge with suspected sensitizing agents confirmed methicillin as the likely offender. Review of the literature relating to methicillin-induced nephropathy suggests a hypersensitivity origin for this disorder, but immunologic and ultrastructural investigation to date has failed to elucidate pathogenesis.
Frozen sections of Herpesvirus hominis-inoculated mouse brain provide excellent antigens for indirect immunofluorescent staining of antibodies to H. hominis in serum. Indirect immunofluorescent staining is a rapid, sensitive, and reproducible method for the measurement of antibodies to H. hominis. The method can be applied to the clinical and epidemiological studies of H. hominis infections.
The antibody response to type III pneumococcal polysaccharide (SS-II) was significantly increased in mice treated with antilymphocyte serum (ALS). BALG/c mice given 0.25 ml of ALS on days -1, 0, and 1 relative to the days of immunization with 0.5 mug of SSS-II had a 20-fold increment (11,383 increased to 199,917) in the number of splenic plaque-forming cells enumerated on day 5 compared with untreated, immunized controls. This effect has been attributed to the elimination of subpopulation of thymus-derived lymphocytes (T cells) that has suppressor function. The present series of experiments relate the augmented antibody response to SSS-II in mice treated with ALS to increased host resistance after infection with Streptococcus pneumoniae, type III (Pn-II). The 50% lethal dose of Pn-III in niminnunized mice was 102 and the 100% lethal dose was 103 organisms. Mice immunized with 0.5 mug of SSS-III and challenged 5 days later with Pn-III were completely protected against a dose of up to 108 organisms. Mice treated with 0.25 ml of ALS on days -1, 0, and 1, immunized with SSS-III on day 0, and challenged with 2.5 X 10(9) Pn-III on day 5 had a mean survival time of greater than 100 h compared with 16 h for immunized non-serum-treated controls. Animals given a single injection of ALS before immunization showed no increase in resistance, whereas mice treated after immunization had significant prolongation of survival times. Untreated, immunized mice challenged with 5 X 10(9), 1 X 5 X 10(8) Pn-II survived 14 to 19 h, whereas ALS-treated animals had mean survival times of 48, 174, and 222 h, respectively. These findings suggest that immunoregulatory T cells may have a biologically significant effect in a narrow zone in which the normal host immune response is insufficient but still potentially capable of providing some additional degree of protection if suppressor cells are elimated.
Primary influenza pneumonia is a disease of high mortality. Differentiation between a bacterial and viral etiology for the pulmonary infiltrates frequently presents a diagnostic dilemma. Rapid diagnosis is essential; and once established, the patient requires careful supportive therapy. This report describes two patients with primary influenza pneumonia complicated by severe respiratory failure. Early diagnosis of the pulmonary infiltrates was accomplished by obtaining bronchial secretions with fiberoptic bronchoscopy and staining them with influenza-A fluorescent conjugate. One patient died of the complications of this illness, despite maximal supportive therapy. The other patient survived the illness and at the time of hospital discharge was showing marked improvement in his exercise tolerance. There was subsequent gradual return of ventilation and gas transport function to normal values.
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