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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Relationships between the MAPI and the MMPI in the assessment of adolescent psychopathology.

Although the Minnesota Multiphasic Personality Inventory (MMPI) and the Millon Adolescent Personality Inventory (MAPI) are both widely used in the clinical assessment of adolescents, no research has examined the interrelationship between these two instruments. We investigated MMPI and MAPI responses from 199 adolescents assessed at entrance to inpatient or outpatient psychiatric programs in Florida and Virginia. Univariate correlation analyses identified areas of significant associations between these measures, with coefficients ranging widely from -.70 to .72. Substantial diagnostic differences were found between these instruments. The MAPI, for example, yielded no depression-related diagnoses, but produced many more adjustment disorder and personality disorder diagnoses than the MMPI. The rates of diagnostic assignment agreements between diagnoses produced by clinical judgment, MMPI findings, and MAPI interpretive reports were typically quite low.

Adjustment Disorders↗
PubMed1992

Changes in the self-reported consistency of normal habitual sleep duration of college students (1978 and 1992).

Changes in the consistency of self-reported sleep habits within two large samples of 763 and 782 college students were assessed for 1978 and 1992. Noteworthy changes over the 14-yr. period included significant decreases in the percentage of students who claimed stable (> or = 5-year) sleep-duration habits and the percentage reporting satisfaction with their sleep.

Follow-Up Studies↗
PubMed1992

Malignant hyperthermia: a review.

Malignant hyperthermia (MH) is a rare genetic myopathy that was first described as a fatal complication of general anesthesia in 1960. It is estimated to affect approximately 1 in 15,000 pediatric patients and 1 in 40,000 adult middle-aged patients. The mode of transmission is genetic: the severest form is autosomal dominant, and the less severe, autosomal recessive. Thus, both men and women can have MH, although there is a slightly higher incidence in the male pediatric population. Malignant hyperthermia is usually triggered by halogenated anesthetic agents with or without depolarizing muscle relaxants. The classic diagnostic triad consists of skeletal muscle rigidity, metabolic acidosis, and elevated body temperature. The definitive diagnosis is suspected susceptible individuals is revealed by exposing an intact muscle fiber to caffeine and halothane in varying concentrations. An abnormal contracture response is hypothesized to be the result of an increase in the release of calcium ion from the sarcoplasmic reticulum in response to neuronal stimulation leading to a hypermetabolic state. The mainstay of treatment is dantrolene, given either prophylactically in susceptible patients or immediately whenever a malignant hyperthermic episode is suspected.

Dantrolene↗
PubMed1992

Left ventricular filling pressure in sickle cell anemia.

Indirect left ventricular filling pressures were measured via balloon-tipped catheters in 11 studies of 10 patients with sickle cell anemia and cardiorespiratory symptomatology. Pulmonary capillary wedge pressures exceeded 12 mm Hg in 8 of 11 studies (8 of 10 patients). Mean pressures in mm Hg were: pulmonary capillary wedge, 16.5 +/- 4.2 (SEM); pulmonary artery, 38 +/- 16; brachial artery, 104 +/- 128; and right atrium, 11 +/- 4. The mean cardiac output was 8.8 +/- 3.1 L/min. The mean pulmonary vascular resistance was 237 +/- 122 dynes sec cm-5 and was significantly increased in 4 patients. In addition to further documentation of significantly elevated pulmonary artery pressures in sickle cell anemia patients with cardiopulmonary symptomatology, these data indicate that a contributory role for elevated left ventricular filling pressures must be considered in the pathogenesis of pulmonary hypertension in sickle cell anemia. Elevation of the pulmonary artery pressure was usually associated with elevation of the pulmonary capillary wedge pressure.

Adult↗
PubMed1991

Chronic renal failure in sickle cell disease: risk factors, clinical course, and mortality.

OBJECTIVE: To determine the incidence, clinical course, and risk factors associated with the onset of chronic renal failure in sickle cell anemia and sickle C disease. DESIGN: A prospective, 25-year longitudinal demographic and clinical cohort study. A matched case-control study was conducted to determine risk factors. PATIENTS: A total of 725 patients with sickle cell anemia and 209 patients with sickle C disease who received medical care from the hematology service in a large municipal hospital. Most were observed from birth or early childhood. MEASUREMENTS: Thirty-six patients developed sickle renal failure: 4.2% of patients with sickle cell anemia and 2.4% of patients with sickle C disease. The median age of disease onset for these patients was 23.1 and 49.9 years, respectively. Survival time for patients with sickle cell anemia after the diagnosis of sickle renal failure, despite dialysis, was 4 years, and the median age at the time of death was 27 years. Relative risk for mortality was 1.42 (95% Cl, 1.12 to 1.81; P = 0.02) compared with patients who did not develop renal insufficiency. MAIN RESULTS: Histopathologic studies showed characteristic lesions of glomerular "drop out" and glomerulosclerosis. Case-control analysis showed that ineffective erythropoiesis with increasingly severe anemia, hypertension, proteinuria, the nephrotic syndrome, and microscopic hematuria were significant pre-azotemic predictors of chronic renal failure. The risk for sickle renal failure was increased in patients who had inherited the Central African Republic beta s-gene cluster haplotype. CONCLUSIONS: The pre-azotemic manifestations of hypertension, proteinuria, and increasingly severe anemia predict end-stage renal failure in patients with sickle cell disease. The rate of progression of renal insufficiency is genetically determined. Treatment of the uremic phase has been dismal, underscoring the need for the development of useful pre-azotemic therapeutic modalities.

Adolescent↗
PubMed1991

Clinical, hematologic, and survival data from cats infected with feline immunodeficiency virus: 42 cases (1983-1988).

A retrospective study of stored feline serum samples was done to determine the infection rate of feline immunodeficiency virus in cats in central Missouri. Infected cats were compared with uninfected cats subjected to the same selection criteria on the basis of signalment, clinical signs, and CBC abnormalities. A significant incidence of virus infection was found in male cats. Neither age nor breed predilection could be identified. Infected cats were more likely to be anemic and leukopenic because of neutropenia. Cellulitis and neoplasia were more common in infected cats. A spectrum of disease severity was seen in infected cats ranging from no clinical signs to signs of severe chronic inflammatory disease. Infected cats were more likely to have clinical disease. Mean survival of infected cats was 24.4 months from the time of diagnosis.

Animals↗
PubMed1991

Biosynthesis of platelet activating factor and 1-O-acyl analogues by endothelial cells.

Mass spectrometric procedures have been used to measure 1-O-alkyl-2-O-acetyl-glycero-3-phosphocholine (PAF) and a structural analogue, 1-O-acyl-2-O-acetyl-glycero-3-phosphocholine, biosynthesis in stimulated human umbilical vein endothelial cells (HUVEC). The primary species of acetylated glycerophosphocholine detected were of the 1-O-acyl type, rather than PAF. The amounts of PAF synthesized were much less than reported in earlier studies. In addition, mass spectrometric procedures were used to profile the molecular species of glycerophosphocholine in HUVEC and to determine those species which have arachidonate in the sn-2 position. The pattern of the occurrence of arachidonate in the sn-2 position is very similar to the pattern of synthesis of the acetylated glycerophosphocholines. These results suggest that 1-O-acyl-2-O-acetyl-glycero-3-phosphocholines may have significant but unappreciated biological activities. These results also support the view that glycerophosphocholine molecular species which have arachidonate esterified at the sn-2 position are the immediate precursors for the hydrolysis-acetylation steps which result in the synthesis of sn-2 acetylated glycerophosphocholines, including PAF.

Acetylation↗
PubMed1991

The Escherichia coli DnaK chaperone, the 70-kDa heat shock protein eukaryotic equivalent, changes conformation upon ATP hydrolysis, thus triggering its dissociation from a bound target protein.

The DnaK protein of Escherichia coli and its eukaryotic hsp70 analogues are known to bind some polypeptides and to release or dissociate from them following ATP hydrolysis. Here we demonstrate that hydrolysis (and not simply binding) of nucleotide triphosphates leads to a change in the DnaK protein, from the "closed" to the "open" conformation. A conformational change is not observed with the mutant DnaK756 protein, which is always found in the open conformation. Although ATP is the preferred substrate, the hydrolysis of CTP, GTP, UTP, and dATP also results in DnaK's conversion from a closed to an open conformation. The ability of DnaK to hydrolyze various triphosphates correlates perfectly with its ability to release the bound denatured bovine pancreatic trypsin inhibitor polypeptide.

Adenosine Triphosphatases↗
PubMed1991

Escherichia coli bacteriuria and contraceptive method.

We evaluated the effects of contraceptive method on the occurrence of bacteriuria and vaginal colonization with Escherichia coli in 104 women who were evaluated prior to having sexual intercourse, the morning after intercourse, and 24 hours later. After intercourse, the prevalence of E coli bacteriuria increased slightly in oral contraceptive users but dramatically in both foam and condom users and diaphragm-spermicide users. Twenty-four hours later, the prevalence of bacteriuria remained significantly elevated only in the latter two groups. Similarly, vaginal colonization with E coli was more dramatic and persistent in users of diaphragm-spermicide and foam and condoms. Vaginal colonization with Candida species, enterococci, and staphylococci also increased significantly in diaphragm-spermicide users after intercourse. We conclude that use of the diaphragm with spermicidal jelly or use of a spermicidal foam with a condom markedly alters normal vaginal flora and strongly predisposes users to the development of vaginal colonization and bacteriuria with E coli.

Adult↗
PubMed1991

Sensitive detection of DNA modifications induced by cisplatin and carboplatin in vitro and in vivo using a monoclonal antibody.

An assay that is based upon a monoclonal antibody (ICR4) is described that enables the quantitation of cisplatin-induced adducts on DNA down to 3 nmol Pt/g DNA (i.e., 1 Pt adduct/10(6) bases), the level necessary to produce toxic effects in cells in vitro and in vivo, using just a few micrograms of DNA. Detection is possible below this level (although probably not necessary for in vivo studies) but the cross-reactivity of unmodified DNA sequences complicates absolute quantitation of adducts. Therefore, it will be possible to investigate the distribution of clinically useful platinum drugs in patients undergoing chemotherapy. Rats of strain F344 appeared to be the best, among several tested, for the production of antibodies to modified DNA, and they were used for the production of hybridomas. Fifteen hybridomas which secreted antibodies that bound to DNA that was highly modified with cisplatin but not to normal DNA were obtained. One (ICR4) was chosen for further characterization because of its relatively strong binding to DNA modified to a moderate level with cisplatin. The characterization included the development of a sensitive competitive enzyme-linked immunoabsorbent assay and the use of DNA that had been reacted with cisplatin both in vitro and in vivo. The levels of platination of both types of DNA samples were determined by atomic absorbance spectroscopy. For DNA that had been exposed to cisplatin in vitro, 50% inhibition of antibody binding was caused by about 15 fmol of total DNA-bound Pt/assay well. At moderate levels of platination, heating of the DNA solution at 100 degrees C for 5 min increased its immunoreactivity such that 50% inhibition was caused by 2.5 fmol Pt adducts/well. Pt adducts on DNA extracted from cells that had been treated with cisplatin were less immunoreactive than DNA treated with cisplatin in vitro, but after heating the immunoreactivity increased such that 50% inhibition in the assay was caused by 2 fmol Pt adduct/well. This sensitivity was invariant over a wide range of levels of platinum adduct frequency. DNA adducts formed by the second generation anticancer drug carboplatin were recognized similarly to the adducts formed by cisplatin, but those formed by the clinically inactive trans-diamminedichloroplatinum(II) or chloro(diethylenetriamine)-platinum(II)-chloride were not significantly immunoreactive. Control DNA cross-reacted in the competitive assay but the immunoreactivity per mol base was 10(7) times lower than the immunoreactivity of cisplatin adducts.

Animals↗
PubMed1991

Evaluation of NaOH treatment of human dura mater implants to obviate Creutzfeldt-Jakob disease transmission.

One of the few disinfectants known to inactivate the causative agent of Creutzfeldt-Jakob Disease is NaOH. In this study, NaOH was evaluated as a possible routine treatment for human dura mater alloimplants. Use of high concentration NaOH (1 M) resulted in protein loss and macroscopic changes to the tissue. Lower concentrations (0.1 M), although exhibiting little direct detrimental effect, greatly increased the susceptibility of the tissue to collagenase digestion. The use of NaOH treated commercial or institutionally prepared human dura mater should be approached with caution.

Creutzfeldt-Jakob Syndrome↗
PubMed1991

Comparison of acellular and whole-cell pertussis-component diphtheria-tetanus-pertussis vaccines in infants. The APDT Vaccine Study Group.

In a multicenter, double-blind, randomized, longitudinal study, 252 children received licensed Lederle diphtheria-tetanus toxoids and pertussis vaccine adsorbed (DTP) at 2, 4, and 6 months of age, and 245 children received a DTP vaccine with the Lederle/Takeda acellular pertussis component (APDT) at the same ages. Both groups of children received APDT vaccine at 18 months of age. After each of the first three immunizations, APDT vaccine recipients had fewer local and systemic reactions than did DTP vaccinees. Reactions after the 18-month APDT vaccination were minimal in severity regardless of the vaccine previously received. Antibody responses to lymphocytosis-promoting factor and agglutinogens were more pronounced in DTP recipients; however, APDT recipients had a better serologic response to filamentous hemagglutinin, and responses to the 69K protein were equivalent. This APDT vaccine produces fewer reactions than the standard whole-cell DTP vaccine. The protective significance of the serologic responses to the APDT vaccine is unknown, but the greater response to filamentous hemagglutinin and equivalent response to the 69K protein compared with those to DTP vaccine seem promising.

Agglutination Tests↗
PubMed1991

Multifactorial assessment of bulimia nervosa.

We investigated a multifactorial approach to the assessment of bulimia nervosa by means of hierarchical factor analysis. Two hundred forty-five bulimia nervosa patients and 68 patients with either anorexia nervosa or eating disorders not otherwise specified were administered a self-report battery that was organized into 21 dimensions relevant to eating disorder patients. When dimensions from this battery were subjected to hierarchical factor analysis, support for bulimia nervosa as a unique diagnostic category was obtained. However, the emergence of 3 secondary factors and 6 primary factors suggests that bulimia nervosa can also be described more complexly. The emergence of a multifactorial model of bulimia nervosa that incorporates several existing undimensional models suggests the potential for both divergent and complicated clinical presentation in bulimia nervosa patients.

Bulimia↗
PubMed1991

Effects of extradural anaesthesia on umbilical and uteroplacental arterial flow velocity waveforms.

Flow velocity waveforms were recorded from the umbilical artery and uteroplacental arterial circulations of 15 women undergoing elective Caesarean section under extradural anaesthesia. The systolic: diastolic ratios of the flow velocity waveform were determined before and after extradural block. Extradural block did not alter fetal or maternal heart rates; however, umbilical artery systolic:diastolic ratio decreased from a mean (SD) of 2.4 (0.42) to 2.26 (0.38) (P = 0.049). There were no significant changes in the uteroplacental systolic:diastolic ratios. These results were compared with those from a control group in which no statistically significant changes in maternal and fetal systolic:diastolic ratios or heart rates were observed. The application of a pulse correction factor to standardize the data to fixed maternal and fetal heart rates had little effect on the significance of the findings. Extradural block in normal pregnant women during late gestation was associated with a small reduction in umbilical artery systolic:diastolic ratios, suggesting a decrease in downstream fetoplacental vascular resistance.

Adult↗