Search PubMed⌕ Search

Biomedical subjects

M T Johnson

Publications and source records attributed to M T Johnson.

11 recordsLinked to original sources
PubMed1991

Modulation of the stretch reflex during volitional sinusoidal tracking in Parkinson's disease.

Sinusoidal visually-guided wrist tracking, in normal and parkinsonian subjects, was perturbed by torque transients every 90 degrees throughout the movement. Long-latency stretch reflex and volitional EMG amplitude modulations were assessed as functions of the tracking phase. Reflex modulation during tracking, both in wrist flexor and extensor muscles, was found to differ significantly between parkinsonian and normal subjects. In the parkinsonian group, the abnormality consisted of an increased reflex activity during tracking phases in which the muscle was lengthening. At these phases the reflex generated torque is opposite in direction to the volitionally generated torque and the tracking movement. No differences in the unperturbed volitional EMG modulation were observed between groups for this error constrained tracking paradigm. Significant correlations were found between ratings of bradykinesia and the amount of abnormal reflex modulation in the wrist flexor. These data suggest that a component of bradykinesia results from a defective coordination of supraspinal reflex and volitional control systems.

Aged↗
PubMed1991

Computer-based program for identifying medication orders requiring dosage modification based on renal function.

A computer-based program that enables staff pharmacists to quickly review medication orders written for renally impaired patients is described. Medication orders requiring dosage modification based on the renal function of the patients for whom they were written were being identified by a medical staff-approved pharmacist intervention program. However, staff pharmacists were unable to assess the orders easily and rapidly because of a lack of readily available patient data. In response, a computer-based intervention program was developed. Specific dosage guidelines for renally eliminated drugs in patients with renal dysfunction were entered into the pharmacy computer. An interface with the laboratory computer enables the pharmacy computer to access creatinine concentration or clearance values, perform calculations if necessary, and alert pharmacists to specific drug orders that may require modification. Such medication orders are flagged by the pharmacy computer during order entry. When a staff pharmacist judges that intervention is needed, he or she telephones the ordering physician or sends a note to the patient's nursing station. Over a two-month period, 1485 orders were identified as being potentially inappropriate. Physicians were contacted about 191 of the flagged orders, and they accepted the pharmacist's recommendation for 141 (74%) of these orders. The interventions resulted in a drug acquisition cost saving of $7082 over the two-month period. A computer-based program enabled staff pharmacists to easily and rapidly identify orders for renally eliminated agents that required modification, reduced the risk of adverse reactions, trimmed costs, and promoted the clinical dimension of pharmacy practice.

Clinical Pharmacy Information Systems↗
PubMed1990

Influence of glottic mechanism on pulmonary function after acute lung injury.

We measured arterial gas tensions, respiratory timing, and intratracheal pressure in 12 rabbits to investigate the consequences of translaryngeal intubation with normal and subsequently injured lungs. Data were collected before, during, and after intubation. Intubation in normal rabbits precipitated no untoward effects on gas exchange or respiratory phase timing. However, there was significant elevation of subglottic pressure during expiration following extubation. Central venous injection of oleic acid (0.08 ml/kg) induced an acute lung injury that after 24 h was characterized by reduced PaO2 and dynamic lung-thorax compliance and tachypnea. Intubation in animals with acute lung injury was associated with a significant decline in arterial oxygenation, tachypnea, and increased PCO2. Expiratory tracheal pressure and expiratory time were greater and PaCO2 and respiratory rate were lower following extubation. We conclude that translaryngeal intubation following acute lung injury exacerbates already compromised pulmonary function by preventing a compensatory expiratory braking maneuver by the glottic apparatus.

Animals↗
PubMed1978

Purification and properties of a nucleoside diphosphosugar: NAD+ 2-hexosyl oxidoreductase.

Penicillium charlesii contains a nucleoside diphosphosugar: NAD 2-hexosyl oxidoreductase that oxidizes UDPgalactose (UDP-Galp), ADPribose [1,2] and UDPglucose (UDP-Glc). Dithiothreitol, NAD and 0.25 M NaCl but not nucleoside diphosphates stabilize the enzyme activity. The enzyme was purified and separated on polyacrylamide disc gels by electrophoresis into one major and eight minor bands of protein. Oxidoreductase activity was located in the major and three of the minor bands of protein. Each of these proteins catalyze the oxidation of UDPGalp, ADPribose and UDP-Glc.

Carbohydrate Dehydrogenases↗
PubMed1978

Fixatives and methods of fixation in selected tissues of the laboratory rat.

The histologic appearances of tissues fixed by immersion and perfusion were compared, as well as the effects of these different fixatives: 10% neutral buffered formalin, Carnoy's fluid, and Bouin's fluid. Intravascular perfusion provided better tissue preservation than fixation by immersion. The quality of preservation by neutral buffered formalin was equal to that of Carnoy's fluid and Bouin's fluid, but the overall staining quality of the latter two was judged to be superior.

Animals↗
PubMed1977

Frameshifts and frameshift suppressors in Saccharomyces cerevisiae.

Using ICR-170 as a mutagen, we have induced a set of mutations in yeast which exhibit behavior similar to that shown for bacterial frameshift mutations. Our genetic study shows that these mutations are polar; the polarity can be relieved by internal suppressors; they revert with acridine half-mustards and are not suppressed by known nonsense suppressors. However, they are suppressed by other dominant external suppressors, which fall into two mutually exclusive groups. Five genetically distinct suppressors were obtained for one of these groups, using co-reversion of two frameshift markers. Three of these are lethal in combination with each other and show a reduction in the GLY3 tRNA peak on a Sepharose 4B column. A fourth suppressor shows an altered chromatographic profile for GLY1 tRNA. We suggest that this group of suppressors represent mutations in the structural genes for the isoaccepting glycyl-tRNA's. Two other suppressors (one linked to the centromere of chromosome III) were found to suppress a second group of frameshifts. Genetic and biochemical studies show that the nonMendelian factor (PSI+) increases the efficiency of some frameshift suppressors.

Genes↗
PubMed1975

Treatment of varicella-zoster virus infections with adenine arabinoside.

Twenty-three patients with complicated varicella-zoster virus infections were treated with adenine arabinoside. Of 14 patients with herpes zoster, 13 had malignancy treated with irradiation and cytotoxic agents or steroids. Although the duration of active vesicle formation in these patients ranged from two to 14 days before therapy, no new lesions appeared after the fourth day of treatment with adenine arabinoside. Zoster encephalitis developed in one patient on the third day of treatment, and severe postherpetic neuralgia was seen in three patients. Of nine treated patients with primary varicella, six improved, including five with evidence of varicella pneumonia. Two of the three patients with varicella who died were immunosuppressed and had progressive viral pneumonia with persistently high titers of virus in vesicular fluid; the third pateint was a child with Reye's syndrome. Double-blind controlled studies will be necessary to demonstrate the efficacy of adenine arabinoside in the treatment of infections with varicella-zoster virus.

Adult↗
PubMed1975

Prospective double-blind evaluation of topical adenine arabinoside in male herpes progenitalis.

Thirty-four virologically proven episodes of herpes progenitalis in 32 men were treated in a prospective double-blind study with either adenine arabinoside ointment or an identical-appearing placebo for 7 days. Clinical evaluation and quantitative virological studies were done on days 1, 3, and 8. There was a highly significant correlation between clinical response and quantitative virology. There was no difference in clinical or virological response between drug and control groups. Primary attacks tended to have higher viral excretion over the period of observation. The level of complement-fixing antibody to herpes simplex virus type 2(<1:16 versus >/=1:16) in patients with recurrent disease did not appear to alter the course of viral excretion.

Administration, Topical↗