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Biomedical subjects

R C Johnson

Publications and source records attributed to R C Johnson.

At least 505 records · Page 28Linked to original sources
PubMedDate not supplied

Spatial relationship of the Fis binding sites for Hin recombinational enhancer activity.

Site-specific recombination reactions involve the joining or rearrangement of discrete DNA segments in a highly precise manner. A site-specific DNA inversion regulates the expression of flagellin genes in Salmonella by switching the orientation of a promoter. Analysis of the reaction has shown that, in addition to DNA sequences at the two boundaries of the 1-kilobase invertible segment where strand exchange occurs, another cis acting sequence is required for efficient inversion. This 60-base-pair enhancer-like sequence can function at many different locations and in either orientation in a plasmid substrate. It includes two binding sites for a host protein called Factor II or Fis (refs 4 and 5). Here we have investigated the importance of the spatial relationship between the two Fis binding sites for enhancer activity and have found that the correct helical positioning of the binding sites on the DNA is critical. However, this result could not be accounted for by effects on Fis binding. We propose a model for enhancer function in which the enhancer region acts to align the recombination sites into a specific conformation required for productive synapsis.

Bacterial Proteins↗
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Asians, Asian-Americans and alcohol.

The association of flushing (vasodilation, reddening of the skin) with the alcohol use of Asians and Asian-Americans is examined. Historical changes in alcohol use, recent secular changes in alcohol use, and marked differences in consumption among Asian populations and among Asian-Americans of the same national origins, as well as the lack of reduction of sex differences among flushers, indicate that flushing has little influence on alcohol consumption. Social, psychological, and cultural influences seem to be more adequate explanatory devices with regard to Oriental alcohol use.

Alcohol Drinking↗
PubMedDate not supplied

Risk and protective factors related to native Hawaiian adolescent alcohol use.

The present study examined protective and risk factors in the prediction of alcohol use for Hawaiian and non-Hawaiian (i.e. Caucasian, Japanese, Filipino, 'other') adolescents. Comparable rates of approximately 25% were found for both the Hawaiian and non-Hawaiian samples regarding sometimes drinking too much alcohol. However, Hawaiians reported a statistically significantly higher rate (3.7%) of taking 'a drink in the morning to steady my nerves or to get rid of a hangover' than non-Hawaiians (1.3%). The reason for this is unknown but might indicate a higher rate of dependent alcohol use. The overall results supported the traditional model of protective and risk factors predicting alcohol use (R(2) > 15.0%), with relatively few differences found between the two ethnic groups. Further research is needed in assessing possibly unique cultural variables such as Hawaiian acculturation.

Adolescent↗
PubMedDate not supplied

Isolation techniques for spirochetes and their sensitivity to antibiotics in vitro and in vivo.

Leptospira interrogans can be cultured from blood and cerebrospinal fluid during the first week of leptospirosis and from urine thereafter. Studies of in vitro sensitivity indicate that these organisms are sensitive to most antibiotics. Tetracycline and penicillin G are most often used clinically, although laboratory studies suggest that the bactericidal activity of penicillin G may be inadequate. Treponema pallidum cannot be satisfactorily cultured. It is identified by dark-field microscopy. Studies of in vivo sensitivity show that penicillin G is highly active against the syphilis pathogen. Since syphilis and gonorrhea may occur simultaneously, ceftriaxone, which is as active as penicillin G against T. pallidum but is also active against penicillinase-producing gonococci, is a logical choice for therapy. Borrelia burgdorferi has been cultured from the blood, cerebrospinal fluid, and skin of patients with Lyme disease. In vitro studies have shown tetracycline and erythromycin to be effective against B. burgdorferi and penicillin G to be less so, although all are commonly used clinically. Ceftriaxone has also proven to be highly effective in laboratory studies and for clinical treatment.

Animals↗
PubMedDate not supplied

Effects of ethanol: II. Behavioral sensitivity and acute behavioral tolerance.

Two doses of ethyl alcohol were administered to 48 young male subjects (24 brother-pairs), and placebo doses were administered to five brother-pairs (controls). Dose 1 amount was calculated to result in a peak blood alcohol content (BAC) of 100 mg/100 ml; dose 2 was given when BAC had fallen to one-half the peak BAC resulting from dose 1, in an attempt to raise BAC back to 100 mg/100 ml. Prior to alcohol dosage, baseline measurements were made on a number of behavioral tests. Behavioral performances during metabolism of doses 1 and 2 were compared to baseline performance. Sensitivity to ethanol was indicated by performance decrements on nearly all tests after ethanol dosing. Acute behavioral tolerance to ethanol (ABTE) was indicated for some tests by improved performance after dose 2 compared to performance at a time after dose 1 when BACs were about equivalent. A preliminary search for possible genetic components of sensitivity and ABTE was undertaken by comparing the scores of the brothers.

Adolescent↗
PubMedDate not supplied

Vacuolation in renal tubular epithelium of Cd-1 mice: an incidental finding.

Prominent cytoplasmic vacuoles were observed in renal tubular epithelial cells of the outer medulla in several kidneys from test article-dosed mice (Crl:CD-1 (ICR)BR VAF/PLUS) during routine light microscopic (LM) examination. Because the vacuolar change was detected infrequently and was not found in any control mice from that study, it was not clear whether the vacuolation represented a drug-induced change. To address this question, kidney sections from mice from multiple unrelated studies were examined by LM for similar vacuolar changes. Vacuolation was seen by LM in 2.3% of the control and 2.8% of the test article-dosed mice. Transmission electron microscopy (TEM) was also performed on kidneys with prominent light microscopic vacuoles in 5 control mice and 2 test article-dosed mice to further characterize the vacuoles. Ultrastructurally, the vacuoles contained fibrillar and finely stipled granular material or membranous whorls. Kidneys from control mice lacking light microscopic evidence of vacuolation had smaller vacuoles containing similar material when examined by TEM. Because vacuoles were present in both control mice and test article-dosed mice, it was concluded that the vacuoles were incidental and unrelated to compound administration. These studies also demonstrated that vacuoles can be expected to be observed by LM examination in 2-3% of Crl:CD-1 (ICR)BR VAF/PLUS, mice.

Animals↗
PubMedDate not supplied

Renal changes associated with naproxen sodium administration in cynomolgus monkeys.

Naproxen sodium was administered to cynomolgus monkeys (Macaca fascicularis) by oral gavage at daily doses of 44, 88, or 176 mg/kg for 2 wk (2 monkeys/gender) or of 44 mg/kg for 13 wk (4 monkeys/gender). Body weight loss occurred in at least one monkey in all naproxen sodium-dosed groups in the 2-wk (up to 16% loss) and 13-wk (up to 22% loss) studies. Increases in plasma naproxen concentrations were dose proportional between 44 and 88 mg/kg but were less than dose proportional between 88 and 176 mg/kg. Up to 2-fold increases in creatinine and/or serum urea nitrogen values as well as higher renal weights occurred in monkeys receiving 176 mg/kg for 2 wk or 44 mg/kg for 13 wk. Microscopically, renal changes were observed in all naproxen sodium-dosed groups. Renal findings after 2 wk of exposure included increased interstitial ground substance, tubular dilatation, and tubulointerstitial nephritis; in the 13-wk study, cortical tubular atrophy and interstitial fibrosis were also observed. These studies identify the kidney as the target organ of naproxen sodium in cynomolgus monkeys.

Animals↗
PubMedDate not supplied

Cognitive correlates of hemispheric performance on dichotic tasks.

Older (age 50+) adults were tested twice on three measures of dichotic memory and once on three measures of cognition. Internal consistencies of all three measures generally were adequate. However, test-retest reliabilities, by ear of presentation, were comparatively low for the three dichotic measures. A measure of vocabulary (a left hemisphere dominant cognitive ability) was related to performance on most dichotic tasks. Years of education (an index of left hemisphere mediated crystallized intelligence) was related to performance on left but not right hemisphere function on two of three dichotic tasks. Performance on tests of spatial ability was related to performance on left ear/right hemisphere but not right ear/left hemisphere function on two of three dichotic memory tasks. Individual differences in accuracy of recall and recognition of stimuli presented via dichotic tasks to the right ear/left hemisphere and the left ear/right hemisphere appear to have different cognitive correlates. Right hemisphere performance on dichotic tasks generally shows a significant negative association with age, as did performance on right hemisphere dominant cognitive tasks. On the other hand, most measures of left hemisphere performance showed no decline associated with age.

Age Factors↗
PubMedDate not supplied

Ideal pain relief following laparoscopic cholecystectomy.

In a previous report the effectiveness of intraperitoneal bupivacaine in reducing pain following laparoscopic cholecystectomy was demonstrated. Other methods of pain relief are commonly used but none has been compared following laparoscopic cholecystectomy. In two further studies we have compared the analgesic effect of intraperitoneal bupivacaine against wound infiltration with bupivacaine, and against intraperitoneal bupivacaine with the addition of a non-steroidal anti-inflammatory drug (NSAID) in patients undergoing laparoscopic cholecystectomy. Two consecutive studies were performed. In the first, patients in group 1 were given 20 ml of 0.25% bupivacaine into the peritoneal cavity; patients in group 2 were given 20 ml of 0.25% bupivacaine injected into the trocar wounds. In the second study, patients in group 1 were given 20 ml of 0.25% bupivacaine into the peritoneal cavity; patients in group 2 were given 20 ml of 0.25% bupivacaine into the peritoneal cavity and a diclofenac suppository (100 mg) one hour before surgery. Postoperative pain was assessed with a visual analogue pain scale. There was no difference in pain scores in the two groups in either study. Intraperitoneal bupivacaine is as effective as wound infiltration. The addition of an NSAID makes no difference in the reduction of postoperative pain following laparoscopic cholecystectomy.

Adult↗
PubMedDate not supplied

Intra-ethnic and inter-ethnic marriage and divorce in Hawaii.

A comparison of intra- and inter-ethnic divorce rates in Hawaii showed that inter-ethnic marriages resulted in a higher proportion of divorces than did intra-ethnic marriages when the marriage data used had to do with all marriages occurring in Hawaii. However, a sizeable portion of marriages in Hawaii are of nonresidents who, if they divorce, probably divorce elsewhere. Nonresident marriages are chiefly intra-ethnic marriages of Caucasians. When examining the proportions of divorces to resident marriages, within-group marriages are more at risk than inter-ethnic marriages. As in prior research, persons who marry members of other racial/ethnic groups tend to marry persons from groups with income levels similar to their own. As in previous reports, some cross-ethnic combinations appeared more at risk for divorce than did others. Group income appeared to be a predictor of risk. When considering only resident marriages as related to divorces, those marriages in which the bride was from a higher income group than the groom were at a significantly greater risk for divorce than marriage in which the bride came from an income group lower than that of the groom.

Divorce↗