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Biomedical subjects

B H Johnson

Publications and source records attributed to B H Johnson.

At least 127 records · Page 7Linked to original sources
PubMed1981

Selenium and reproductive function in boars fed a low selenium diet.

A study was conducted with 24 crossbred boars (77.5 +/- 2.8 days of age) to determine the effects of low Se status on various spermatozoal characteristics and on Se concentration in semen, serum and primary and accessory reproductive tissues. All boars were fed a low Se diet (cornstarch and Torula yeast) ad libitum. Twelve boars were injected every 14 +/- 1 days with sodium selenite (.33 mg Se/kg body weight) and 12 served as saline-treated controls (low Se status). At 210 +/- 5 days of age, six boars in each group were slaughtered, and serum and various tissues were collected and assayed for Se. Treated boars had higher concentrations of Se in the serum (P less than .001), kidney (P less than .001), liver (P less than .001), heart (P less than .001), skeletal muscle (P less than .01), testis (P less than .01), epididymis (P less than .05), seminal vesicle (P less than .01), bulbourethral gland (P less than .001) and prostate (P less than .001) tissues. Starting at 230 +/- 4 days of age, semen samples were collected from the remaining boars at 4- to 6-day intervals until a total of four ejaculates had been obtained from all but two boars. There were no significant treatment differences in semen volume, percentage normal spermatozoa, percentage viability or spermatozoa concentration/milliliter; however, for combined semen Se data, treated boars had more Se than control boars in the whole semen (.165 vs .07 ppm, respectively), spermatozoa (.418 vs .199 micrograms/10(9) spermatozoa, respectively) and seminal plasma (.03 vs .007 ppm, respectively). The boars were castrated around 250 days of age, and no differences in testis length, diameter, weight and spermatozoal concentration were found between groups. Additionally, there were no apparent differences in daily gain, daily feed consumed and the feed to gain ratio between control and treated boars. Although concentrations of Se in serum, semen and reproductive tissues were much lower in control boars than in treated boars, no apparent impairment of sperm morphology or viability resulted from low Se status.

Animals↗
PubMed1981

Interrelationships of serum corticosteriods, LH, and testosterone in male bovine.

Temporal interrelationships of endogenous peripheral blood concentrations of corticosteriods (CS), luteinizing hormone (LH), and testosterone(T) were evaluate in bulls. Concentrations of CS, LH, and T were quantitated in blood samples collected at hourly intervals via jugular cannula from four bulls during a single 24-hr period in January and again in June. Alterations in hormone profile characteristics were noted within bulls between January and June. An increased number of LH peaks and increased area beneath entire 24-hr LH profile suggested that LH secretion was higher during the June sampling period than the January sampling period. However, no significant alteration in T secretion in June was observed. as number of T peaks and area under T peaks were essentially unchanged relative to January. An inconsistent relationship between secretion of LH and T was observed in June, with only 47% of LH peaks associated with elevations in concentration of T whereas in January 80% of LH peaks were associated with T peaks. A higher lag correlation over all bulls between concentration of LH at one hour and concentration of T at the subsequent hour for all such combinations throughout the 24-hr period (LAG-LHTCORR) in January (r = 0.45, p less than 0.001) than in June (r = 0.12, p less than 0.24) also indicated that the temporal relationship between LH and T changed between these two periods of time. Coincident with the area beneath entire 24-hr CS profile and the height of CS peaks were greater in June. Prolonged elevations in concentration of CS were observed to be coincident with basal concentrations of LH and T and a negative value was obtained for LAG-CSTCORR in June (r = -0.10) but not in January (r = 0.06). Results of this study indicate that the major effect of LH upon blood concentration if T in the bull is usually exerted within 1 hr of a LH surge. However, failure of some LH peaks to be followed by T peaks suggests that the secretion of LH and T in the bull may be subject to modulation by adrenocortical hormones and other intrinsic and extrinsic factors.

Adrenal Cortex Hormones↗
PubMed1981

Influence of electroejaculation on peripheral blood concentrations of corticosteroids, progesterone, LH, and testosterone in bulls.

Temporal relationships among serum concentrations of corticosteroids (CS), luteinizing hormone (LH), progesterone (P), and testosterone (T) were examined in ten bulls exposed to the stress of electroejaculation (EE). Concentrations of CS and P increased concomitantly among bulls to peak levels by 15 min post-EE and then declined to pre-EE levels between 2 and 4 hr after EE. Total number of LH and T peaks decreased from 24 and 18, respectively, during the 12-hr pre-EE period to 11 and 14 during the 12-h post-EE period. Mean concentration of LH decreased after EE until 4 hr post-EE when episodic LH secretion resumed and concentrations of CS and P had declined to pre-EE levels. Similarly, mean concentration of T declined after EE and then increased 6-8 hr post-EE in response to resumption of LH secretion. The temporal associations of elevated concentrations of CS and P with basal LH and T before EE, absence of T response to endogenous LH peaks, and the temporary absence of episodic LH and T peaks after EE, suggest that endogenous adrenal steroids may modulate secretion of T in the bull.

Adrenal Cortex Hormones↗
PubMed1981

Are convulsant gases also anesthetics?

This study investigated whether the convulsant gas flurothyl deviates from the correlation between anesthetic potency and lipid solubility. Flurothyl (CF3CH2OCH2CF3) produced convulsions in 50% of mice at 0.122 +/- 0.006% atm. Mice often convulsed repeatedly after exposure to flurothyl, the maximum number of convulsions occurring when the concentration was 0.24% atm. Concentrations greater than 0.6% atm produced convulsions immediately after addition of flurothyl, but rarely at later times. An ED50 value for loss of the righting reflex was obtained when the concentration was 1.22 +/- 0.19% atm. The oil/gas partition coefficient was found to be 46.9 for flurothyl at 37 C. The product of righting-reflex ED50 and oil/gas partition coefficient (0.0122 atm x 46.9 = 0.57 atm) is similar to that found for conventional anaesthetics in mice. Therefore, flurothyl does not deviate from the correlation of anesthetic potency and lipid solubility. It was also found that 0.3 to 0.8% atm flurothyl increased isoflurane MAC in dogs, but that 3 to 4% atm flurothyl decreased it. The increase of isoflurane requirement at lower concentrations of flurothyl suggests that anesthetics with a potential to cause convulsions may partly antagonize their own anesthetic effect. The decrease in isoflurane MAC in dogs at higher concentrations of flurothyl also implies that this compound has an anesthetic effect. A structural isomer of flurothyl, iso-Indoklon [(CSF3)2CHOCH3], was only anesthetic and did not have convulsant properties. Its MAC in dogs was 4.60 +/- 0.45% atm, and its righting-reflex ED50 in mice was 2.65 +/- 0.13% atm. The product of iso-Indoklon MAC in dogs and its oil/gas partition coefficient (27.0) was 1.24 atm, and the product of iso-Indoklon righting-reflex ED50 in mice and oil/gas partition coefficient was 0.72 atm. These values are close to those found for conventional anesthetic agents in dogs and mice; thus iso-Indoklon also does not deviate from the correlation between anesthetic potency and lipid solubilities.

Anesthesia, Inhalation↗
PubMed1980

Transport of immunoglobulins from serum into colostrum.

Oligomeric, J-chain-containing immunoglobulins were observed to be transferred selectively from serum into colostrum. These studies suggest that, in the case of the mammary gland secretion, a significant role for extraglandular synthesis of IgA merits consideration. Thus, for example, colostrum may contain antibodies synthesized locally as well as antibodies synthesized in the much larger lymphoid tissues such as the gut lamina propria.

Animals↗
PubMed1980

Rehabilitation of a patient with complete mandibulectomy and partial glossectomy.

Following a number of radiologic and surgical procedures for the treatment of oral cancer, a patient with severe facial disfigurement and alteration of the vocal tract acquired acceptable speech. Consultation among referring physicians and speech pathologists can aid such a patient by facilitating the rehabilitative process through improvement of communicative skills.

Carcinoma, Squamous Cell↗
PubMed1980

Nitrous oxide intensifies the pulmonary arterial pressure response to venous injection of carbon dioxide in the dog.

To determine the effect of nitrous oxide on the body's response to venous carbon dioxide (CO2) embolization, the authors compared changes in mean pulmonary arterial pressure (MPAP) following intravenous injections of CO2 in pentobarbital-anesthetized dogs breathing 100 per cent oxygen (O2) or nitrous oxide--oxygen, 79:21 per cent (N2O). When CO2 was infused intravenously in seven dogs at a rate of 3 ml/kg/min the volume of injected CO2 needed to increase MPAP to 40 per cent above control during breathing of O2 was approximately 5.5 times the volume necessary during inhalation of N2O. In a second group of eight dogs, breathing N2O, compared with O2 or air, resulted in a significantly greater increase and duration of increase in MPAP following a bolus injection of CO2 of 20, 40 or 80 ml. The data suggest that breathing nitrous oxide intensifies and prolongs the effect of CO2 bubbles in blood. While the magnitude of insult following intravenous injection of CO2 is about 6.5 times less than that for a similar volume of air, avoidance of nitrous oxide should be considered in management of patients in whom CO2 embolism is possible.

Animals↗
PubMed1980

Selenium and reproductive function in yearling Angus bulls.

Selenium, (Se) content of selected tissues and semen and various spermatozoa parameters were evaluated in yearling Angus bulls given supplemental Se. Twenty-four bulls were allotted to two treatment groups: control (n-12) and Se (n-12). Se bulls were given an initial 10ml IM injection containing 50 mg of Se, then injections of 30 mg Se at 21-day intervals for 150 days. Pooled Se concentration (ppm) in serum collected at 21-day intervals averaged .01 and .08 (P < .001) for control and Se bulls, respectively. After 5 months of supplementation, eight bulls in each group were electroejaculated, and semen was processed and frozen for subsequent examination. Bulls were slaughtered for collection of testes, epididymides, seminal vesicles, kidney and liver tissues. Se (ppm) in kidney, liver, seminal vesicle, testis, caput, corpus and cauda epididymis of control and Se-treated bulls was, respectively: .84 and 1.27 (P < .005); .1 and .37 (P < .001); .1 and .21 (P < .001); .35 and .42 (P < .005); .39 and .44; .31 and .34, and .71 and .78. Se (ppm) in extended whole semen, the supernatant fraction and sperm pellet fraction from control and Se-treated bulls was, respectively: .07 and .16 (P < .004); .04 and .13 (P < .001), and .03 and .03. Percentage viability of thawed spermatozoa for control and Se-treated bulls was 26.5 and 23.1, respectively. No differences were observed between control and Se-treated bulls with respect to sperm concentration in the testis and caput, corpus and cauda epididymis. Se treatment of yearling Angus bulls increased the Se concentration of various tissues but had no apparent influence on sperm cell viability, number or Se concentration.

Animals↗
PubMed1980

Withdrawal convulsions in mice following nitrous oxide.

Mice may be induced to convulse after (but not prior to) breathing nitrous oxide. We found that the incidence of this withdrawal phenomenon is related to the partial pressure of nitrous oxide. A minimum (threshold) value of about 0.5 atm is necessary and the majority of mice convulse following exposure to 0.9 atm or greater. Exposures of longer than 15 to 30 minutes do not significantly increase the incidence of convulsions at any given partial pressure. The mice remain susceptible to the induction of convulsions for only a brief period after removal from nitrous oxide. Although the duration of susceptibility is slightly increased after exposure to higher partial pressures, susceptibility in almost all cases is lost by 90 minutes. In mice, exposure to nitrous oxide is associated with evidence of physical dependence as evidenced by withdrawal symptoms, symptoms that be related to the appearance of excitement which sometimes follows nitrous oxide anesthesia.

Animals↗
PubMed1979

Temporal relationships among peripheral blood concentrations of corticosteroids, luteinizing hormone and testosterone in bulls.

Interrelationships among peripheral blood concentrations of corticosteroids (CS), luteinizing hormone (LH) and testosterone (T) were evaluated over a 24-hr period in four Angus bulls (18 months of age and 450 kg in body weight). Concentrations of LH and T were determined by radioimmunoassay and concentrations of CS by competitive protein binding assay of blood samples collected via jugular cannula at hourly intervals for 24 consecutive hr. A positive temporal relationship was observed between LH and T as significant positive correlations were obtained between concentrations of LH at one hour and concentrations of T at the subsequent hour in 3 of 4 bulls. Although LH peaks preceded T peaks by 1 hr, variation in this temporal relationship was observed as LH peaks occurred which were not accompanied by T peaks in some bulls. LH peaks were usually preceded by basal or declining concentrations of CS and prolonged elevations in concentrations of CS were often coincident with basal concentrations of LH and T. Negative correlations were obtained between concentrations of CS at one hour and concentrations of LH and T at the subsequent hour. These data describe the positive regulatory role of LH in testicular T production in the bull and suggest that alterations in endogenous concentrations of CS may influence peripheral concentrations of LH and T in the bull.

Journal Article↗
PubMed1978

Naloxone does not antagonize general anesthesia in the rat.

The administration of naloxone 2, 10, 50, or 250 mg/kg intravenously did not alter halothane requirement (MAC) in Sprague-Dawley rats (12 per group). Two rats convulsed when given 50 mg/kg while anesthetized with halothane. In a separate group of awake rats, seven of nine animals convulsed when given naloxone, 100 mg/kg. It is concluded that any effect of naloxone on anesthetic requirement must be small (not significant in our study), and that if an effect exists it is the result of a nonspecific analeptic action of naloxone rather than a specific action at opiate receptors.

Anesthesia, Inhalation↗