Search PubMed⌕ Search

Biomedical subjects

J M Johnson

Publications and source records attributed to J M Johnson.

At least 181 records · Page 10Linked to original sources
PubMed1984

The effect of a single administration of phencyclidine on behavior in the rat over a 21-day period.

The effects of phencyclidine (PCP) (7.0, 11.7, 19.5, 32.6, and 54.4 mg/kg) on locomotor activity, stereotyped behavior (circling, backing up, and weaving frequency), and rotarod performance were evaluated. In addition, the frequency of other PCP-induced abnormal behaviors (head in corner, arched back, and cataleptic freeze) was determined. All doses of PCP produced a significant increase in locomotor activity and stereotyped behavior as well as an impairment of rotarod performance. Both the duration and the time to peak effects (with the exception of rotarod performance) of these PCP-induced behavioral changes appeared to be dose dependent. The delay in attaining peak effects for locomotor activity and stereotypy was attributed to PCP-induced gross motor ataxia, which became more severe and long lasting with increasing dose. Although the longest period of time that significant changes were seen in locomotor activity, stereotyped behavior, and rotarod performance was 12 hr, sporadic recurrences of stereotypy and a significant increase in cataleptic freeze were observed in the high-dose groups (19.5, 32.6, and 54.4 mg/kg) up to 21 days postadministration. These persistent behaviors (stereotypy and cataleptic freeze) are not unlike certain of the prolonged behaviors seen in man with PCP overdose (catatonic stupor along with repetitive orofacial and limb movements).

Animals↗
PubMed1984

Pharmacological activity of the basic fraction of marihuana whole smoke condensate alone and in combination with delta-9-tetrahydrocannabinol in mice.

This basic fraction (BF) of marihuana whole smoke condensate was subjected to pharmacological testing in males, Swiss-Webster mice. In a general pharmacological activity screen looking at behavioral, neurologic, and autonomic parameters, BF, at iv doses of 5, 10, and 20 mg/kg, caused impairment of visual placing, increase in tail pinch response, decrease in tail elevation, and induction of piloerection. These effects, although statistically significant, were slight and not consistently dose dependent. In a second study with doses ranging from 10 to 29 mg/kg, BF caused a decrease in spatial locomotion, rearing behavior, and urination incidence. In a third study, body temperatures of mice were measured periodically for 2 hr following administration of BF (1.2, 2.4, and 4.8 mg/kg) alone or in combination with 1.0 mg/kg delta-9-tetrahydrocannabinol (THC). BF did not alter body temperature, nor did it affect THC-induced hypothermia. These results, although suggesting that the basic fraction of marihuana whole smoke condensate has pharmacological activity in mice, offers little evidence for the presence of highly active compounds.

Animals↗
PubMed1984

The cervical cap: a retrospective study of an alternative contraceptive technique.

A follow-up study on 130 women fitted with a cervical cap over a 12-month period drew a response rate of 43% (56 respondents). The group was young, well educated, and highly motivated. The failure rate was 16.9 per 100 women years (Pearl method), with inconsistent use and dislodgement being of major importance. The continuation rate was 75% (minimum 3 months of use), and 84% expressed satisfaction with the method. No significant side effects or risks to health were encountered. The conclusion is that there is a significant demand for alternative contraceptive methods among a select group of women. However, in the present state of knowledge, use of the cap should probably not be encouraged as a primary means of contraception, but should be reserved for those women with multiple contraceptive problems or for highly motivated women who seek out this means, understand its limitations, and can accept the relative uncertainty of its effectiveness.

Adult↗
PubMed1984

The neuroteratogenicity of procarbazine in the rat: behavioral, morphological, and neurochemical aspects.

Pregnant female Sprague-Dawley rats were treated from day 12 through day 15 of gestation with procarbazine, an antineoplastic drug, and their offspring were subjected to tests of locomotor development and behavior. Treatment levels ranged from 0.5 mg/kg/day, a dose that produced no abnormalities, to 10 mg/kg/day, a dose that caused a marked micrencephaly in the absence of other teratological changes. Despite marked morphological brain changes, preweaning locomotor development, as assessed by open-field swimming activity and vertical grid climbing, was normal in all offspring. Post-weaning passive avoidance learning and retention were also normal. Groups that had been treated prenatally with teratogenic doses (5.0 and 10.0 mg/kg/day) displayed less rearing behavior in the open field, while ambulation in the periphery of the open field arena was unaffected. Groups treated with subteratogenic doses (0.5 and 1.0 mg/kg/day) did not differ from control. In addition to the behavioral studies, sodium-dependent high-affinity choline uptake and choline acetyltransferase activity (CAT) were measured (per mg protein) in the cortex and hippocampus of animals that had been exposed prenatally to either teratogenic or subteratogenic doses of procarbazine. In spite of a substantial reduction in size of both brain structures in the group receiving a teratogenic dose, choline uptake and CAT did not differ from control.

Abnormalities, Drug-Induced↗
PubMed1984

Carotid surgery without angiography.

We propose that circumstances exist in which angiography is not necessary or is unwarranted for the diagnosis and treatment of carotid arterial disease. High quality real-time B-mode ultrasonographic imaging, combined with both pulsed gated, and continuous wave Doppler analysis, shows a remarkably close correlation with the pathologic abnormality identified at operation. Scanning in the vascular laboratory not only provides quick, noninvasive, accurate assessment of the atherosclerotic disease, it can also provide plaque and blood flow detail not previously attainable. Carotid surgery can be effectively and safely performed in selected patients with the aid of ultrasonography and Doppler analysis without the need for invasive angiographic imaging.

Aged↗
PubMed1984

Psychiatric uses of antiadrenergic and adrenergic blocking drugs.

Most clinicians are aware of the unwanted behavioral effects which may accompany the use of drugs that affect noradrenergic functioning in the treatment of hypertension. However, it is not generally appreciated by psychiatrists that these drugs have many potential therapeutic uses in psychiatry and are potent adjuncts to traditional psychotropic drugs. When administered appropriately by a psychiatrist, antiadrenergic and adrenergic blocking drugs can be used for treatment of disorders of thought, mood, anxiety, and movement. This paper reviews the pharmacology of four of these medications. The literature is reviewed for each drug. Although the mechanisms of action of these antihypertensives differ, their common effects on noradrenergic functioning often result in behavioral changes.

Adult↗
PubMed1984

Laser-Doppler measurement of skin blood flow: comparison with plethysmography.

We compared laser-Doppler velocimetry with plethysmographically determined changes in skin blood flow (SkBF) in five studies on four men. Increments in SkBF were induced by raising whole-body skin temperature to 39 degrees C for 50-70 min. We found laser-Doppler blood flow (LDF) to correlate well with total forearm blood flow (FBF) within each study (r = 0.94-0.98), but the relationship varied among studies. Thus the slopes for the LDF vs. FBF relationship varied from 40 to 122 mV X ml-1 X 100 ml X min. The value for LDF at zero FBF, extrapolated from the regression relationships, ranged from 246 to 599 mV above the value for LDF set with the probe on a stationary object. The value for LDF when blood flow to the arm was mechanically occluded ranged from 110 to 230 mV. In a second series, we measured the LDF values from six sites on forearms of each of four normothermic men. There was marked regional variation, with 1.8- to 5.7-fold ranges in LDF within a given subject. Values for LDF during occlusion of the forearm were more consistent within and between subjects. Thus LDF appears to provide a good indicator of the response pattern of SkBF from the region of illuminated skin. However, variability in the relationship to total SkBF (probably arising from variation in the number of perfused capillaries in the small volume of tissue) and uncertainties in the value of LDF at zero SkBF make quantitative use difficult.

Adult↗
PubMed1984

Reflex regulation of sweat rate by skin temperature in exercising humans.

To find whether sweat rate (SR) and forearm skin blood flow ( SkBF ) were reflexly affected by skin temperature (Tsk) we used water-perfused suits to rapidly elevate Tsk during exercise. With this elevation in Tsk, there was a period of little net change in esophageal temperature (Tes) but marked responses in SR and SkBF . During this period a rise in Tsk of 4.2 +/- 0.3 degrees C was associated with an increase in SR of 0.44 +/- 0.09 mg X cm-2 X min-1 and an increase in SkBF of 3.27 +/- 0.42 ml X 100 ml-1 X min-1. Multiple linear regression analysis as well as comparison with control studies in which Tsk was kept cool also reveal a consistent role for Tsk in the reflex regulation of SR and SkBF . Responses in SR and FBF were much more marked at levels of Tsk below 33 degrees C. Below a Tsk of 33 degrees C, SR rose 0.30 +/- 0.06 mg X cm-2 X min-1 per degrees C rise in Tsk, whereas above 33 degrees SR rose only 0.05 +/- 0.01 mg X cm2 X min per degrees C. FBF rose 2.81 +/- 0.60 and 0.77 +/- 0.18 ml X 100 ml-1 X min-1 per degrees C rise in Tsk at the lower and upper ranges of Tsk, respectively.

Adult↗
PubMed1984

Effect of high local temperature on reflex cutaneous vasodilation.

We examined the effect of high local forearm skin temperature (Tloc) on reflex cutaneous vasodilator responses to elevated whole-body skin (Tsk) and internal temperatures. One forearm was locally warmed to 42 degrees C while the other was left at ambient conditions to determine if a high Tloc could attenuate or abolish reflex vasodilation. Forearm blood flow (FBF) was monitored in both arms, increases being indicative of increases in skin blood flow (SkBF). In one protocol, Tsk was raised to 39-40 degrees C 30 min after Tloc in one arm had been raised to 42 degrees C. In a second protocol, Tsk and Tloc were elevated simultaneously. In protocol 1, the locally warmed arm showed little or no change in blood flow in response to increasing Tsk and esophageal temperature (average rise = 0.76 +/- 1.18 ml X 100 ml-1 X min-1), whereas FBF in the normothermic arm rose by an average of 8.84 +/- 3.85 ml X 100 ml-1 X min-1. In protocol 2, FBF in the normothermic arm converged with that in the warmed arm in three of four cases but did not surpass it. We conclude that local warming to 42 degrees C for 35-55 min prevents reflex forearm cutaneous vasodilator responses to whole-body heat stress. The data strongly suggest that this attenuation is via reduction or abolition of basal tone in the cutaneous arteriolar smooth muscle and that at a Tloc of 42 degrees C a maximum forearm SkBF has been achieved. Implicit in this conclusion is that local warming has been applied for a duration sufficient to achieve a plateau in FBF.

Adult↗
PubMed1984

Modification of the cutaneous vascular response to exercise by local skin temperature.

This study examined how local forearm temperature (Tloc) affects the responsiveness of the cutaneous vasculature to a reflex drive for vasoconstriction. We observed responses in forearm blood flow (FBF) and arterial blood pressure to a 5-min bout of supine leg exercise of moderate intensity (125-175 W) after the forearm had been locally warmed to 36, 38, 40, or 42 degrees C for 48 min. With exercise, FBF fell by 1.82 +/- 0.23, 4.06 +/- 0.58, and 3.64 +/- 1.48 ml X 100 ml-1 X min-1 at 36, 38, and 40 degrees C, respectively, and rose by 2.16 +/- 0.57 ml X 100 ml X min-1 at a Tloc of 42 degrees C (mean +/- SE). Forearm vascular conductance (FVC) fell with the onset of exercise by averages of 2.77 +/- 0.57, 7.02 +/- 0.51, 5.36 +/- 0.85, and 4.17 +/- 0.79 ml X 100 ml-1 X min-1 X 100 mmHg-1 at 36, 38, 40, and 42 degrees C, respectively. Second-order polynomial regression analysis indicated that the reductions in FVC were greatest near a Tloc of 39 degrees C and that at a Tloc of 40 or 42 degrees C the cutaneous vasoconstrictor response to the onset of exercise is attenuated. Although elevated Tloc can be used to increase base-line FBF levels to make cutaneous vasoconstrictor responses more obvious, the direct effects of Tloc on this response must also be considered. We conclude that the optimum Tloc for observing reflex cutaneous vasoconstriction is near 39 degrees C.

Adult↗
PubMed1983

Metal complexes as mediator-titrants for electrochemical studies of biological systems.

Various redox-active metal complexes were evaluated electrochemically for stability, reversibility, and general utility as mediator-titrants in the 0 to + 1.0 V vs standard hydrogen electrode range. Those complexes which were evaluated and appear to be useful in potentiostatic or potentiometric techniques are Ru(bpy)3(CIO4)2, Ru(bpy)2(im)2, Os(bpy)3(NO3)2, K2Fe(phen)(CN)4, Co(phen)3Cl2, and Co(terpy)2Cl2.

Chemical Phenomena↗
PubMed1982

Prevention and management of polytetrafluoroethylene graft complications in peripheral vascular reconstruction.

The use of expanded PTFE grafts as a vascular substitute has been well established. PTFE is an acceptable alternative for patients in whom the saphenous vein is unusable. Nonreinforced PTFE grafts do a better job of resisting infection, permitting cellular ingrowth, and allowing the development of a true neointima. During a 6 year period ending in April 1981, 129 grafts were placed in various positions. Most of these were placed primarily in the femoropopliteal position. One death occurred as a direct result of the surgery. Only two infections were encountered, both were delayed and patient-induced. There were no true aneurysms in the PTFE grafts of our patients. The use of smooth noncrushing clamps applied gently with just enough pressure to stop blood flow will lessen the likelihood of aneurysmal formation. Careful surgical technique can minimize problems. False aneurysm in vascular reconstruction can largely be prevented by the proper establishment of hemostasis at the suture line. Selection of an appropriate needle and suture along with the use of proper technique in their placement will help provide the best possible results. One should follow the curve of the needle at the time of suturing to help prevent elongation of the suture holes, which may contribute to difficulties in establishing hemostasis at the suture line. Thrombosis is the most common problem associated with the use of this graft; correction requires careful balloon catheter techniques. Salvage of the graft can be obtained by endarterectomy, patch grafting, or jump grafts so that the entire prosthesis does not have to be replaced.

Aneurysm↗
PubMed1982

Ultrasonographic screening for evaluation and follow-up of carotid artery ulceration. A new basis for assessing risk.

Routine ultrasonographic screening and examination of patients with and without specific symptoms of carotid artery disease now provides greater understanding of the natural history of the disease. In one year, 194 ulcers were detected, classified, and followed. No initially asymptomatic ulcer shallower than 2 mm later became asymptomatic, and it is than 2 mm later because asymptomatic, and it is concluded that a trial of antiplatelet therapy in these patients would be inconclusive. More than a third of the initially asymptomatic ulcers from 2 to less than 4 mm in depth gave rise to lateralizing symptoms that required surgery. The effects of antiplatelet therapy in this vulnerable population could be readily followed by ultrasonographic monitoring. All patients with ulcers 4 mm or more in depth were initially symptomatic and so required surgery.

Carotid Artery Diseases↗