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Biomedical subjects

T Gordon

Publications and source records attributed to T Gordon.

At least 181 records · Page 10Linked to original sources
PubMed1986

Effect of ozone and histamine on airway permeability to horseradish peroxidase in guinea pigs.

Airway permeability was studied in groups of male guinea pigs at 2, 8, and 24 h after a 1-h exposure to 1 ppm ozone or at 2 h after a 1-h exposure to filtered air (control). Intratracheal administration of 2 mg horseradish peroxidase (HRP) was followed by blood sampling at 5-min intervals up to 30 min. The rate of appearance of HRP in plasma was significantly higher at 2 and 8 h after ozone exposure than that found in animals examined 2 h after air exposure or 24 h after ozone exposure. A dose of 0.12 mg/kg of subcutaneous histamine given after the 15 min blood sample significantly increased the already elevated permeability seen at 2 h post ozone, but had no effect on animals exposed to filtered air 2 h earlier or to ozone 24 h earlier. No difference was seen in the amount of subcutaneous radiolabeled histamine in the lungs of animals exposed 2 h earlier either to air or to ozone. These data indicate that a short-term exposure to ozone produced a reversible increase in respiratory epithelial permeability to HRP in guinea pigs. The potentiation of this increased permeability by histamine may be another manifestation of ozone-induced hyperreactivity.

Animals↗
PubMed1986

Rapid development of cerebral atrophy in systemic lupus erythematosus.

A 21-year-old female is described who developed severe cerebral lupus 9 months after the onset of her disease. A dramatic change in her CT brain scan from normal to gross cerebral atrophy was observed in the month following onset of her cerebral disease. This patient developed hepatitis during the course of her hospitalization. This is an unusual manifestation of systemic lupus. The patient's serum also contained anti-Sm antibodies. This is a relatively infrequent finding in the serum of lupus patients outside the United States.

Adult↗
PubMed1986

Reinnervation of the lateral gastrocnemius and soleus muscles in the rat by their common nerve.

To determine whether there is any specificity of regenerating nerves for their original muscles, the common lateral gastrocnemius soleus nerve (l.g.s.) innervating the fast-twitch lateral gastrocnemius (l.g.) and slow-twitch soleus muscles was sectioned in the hind limb of twenty adult rats. The proximal nerve stump was sutured to the dorsal surface of the l.g. muscle and 4-14 months later, the contractile properties of the reinnervated l.g. and soleus muscles and their single motor units were studied by dissection and stimulation of the ventral root filaments. Contractile properties of normal contralateral muscles were examined for comparison and motor units were isolated in l.g. and soleus muscles for study in a group of untreated animals. Measurement of time and rate parameters of maximal twitch and tetanic contractions showed that the rate of development of force increased significantly in reinnervated soleus muscles and approached the speed of l.g. muscles but rate of relaxation did not change appreciably. In reinnervated l.g. muscles, contraction speed was similar to normal l.g. muscles but relaxation rate declined toward the rates of relaxation in control soleus muscles. After reinnervation by the common l.g.s. nerve, the proportion of slow motor units in l.g. increased from 10 to 31% and decreased in soleus from 80 to 31%. The relative proportions of fast and slow motor units in each muscle were the same as the proportions of fast and slow units in the normal l.g. and soleus muscles combined. It was concluded that fast and slow muscles do not show any preference for their former nerves and that the change in the force profile of the reinnervated muscles is indicative of the relative proportions of fast and slow motor units: fast units dominate the contraction phase and slow units the relaxation phase of twitch and tetanic contractions of the muscle.

Animals↗
PubMed1986

Innervation and function of hind-limb muscles in the cat after cross-union of the tibial and peroneal nerves.

Peripheral nerves to flexor (common peroneal) and extensor (tibial) nerves in a hind limb of seven 2-6 month old cats were cut and cross-united to study the plasticity in the spinal cord. The extent to which motoneurones from extensor and flexor motor pools were misdirected to their antagonistic muscles was determined by measuring the potentials generated at the spinal roots from the crossed nerves. The axons contributing to the extensor nerves normally leave the cord in the L7 and S1 ventral and dorsal roots while the axons contributing to the flexor nerves normally leave the cord in the L6 and L7 ventral and dorsal roots. Following cross-union, medial gastrocnemius (m.g.) and lateral gastrocnemius-soleus (l.g.s.) nerves were primarily supplied by L6 and L7 ventral and dorsal roots, and common peroneal (c.p.) nerves were primarily supplied by L7 and S1 ventral and dorsal roots. A method for quantifying the completeness of cross-reinnervation was developed. The pattern of e.m.g. activity in cross-reinnervated muscles during locomotion was primarily determined by the innervating nerve with the reinnervated flexor muscles being activated during the extensor phase. However, the cross-reinnervated extensor muscles showed evidence of extensor activity in addition to the double-burst pattern typical of flexor nerves. This extensor activity was more prominent when the nerve cross was less complete. We conclude that during locomotion the activity of spinal motoneurones was not substantially modified by inappropriate peripheral connexions, even when the nerve cross was carried out in young animals. This conclusion is discussed in relation to previous studies which suggested some degree of functional modification.

Action Potentials↗
PubMed1986

Organization of motor units following cross-reinnervation of antagonistic muscles in the cat hind limb.

Peripheral reorganization of nerve and muscle properties was studied following misdirection of regenerating axons to foreign muscles. The tibial nerve, which innervates all of the distal extensor muscles, was cross-united with the common peroneal nerve, which innervates all of the distal flexor muscles, in one hind limb of seven 2-6 month old cats. After 18-24 months the properties of the motor units in the reinnervated triceps surae muscles were studied by dissection and stimulation of the ventral root filaments. The normal size relationships were re-established in reinnervated medial gastrocnemius (m.g.) and lateral gastrocnemius-soleus (l.g.s.) muscles in so far as motor unit force was directly correlated with the extracellularly recorded amplitude of the axon potential and with contractile speed. The range of sizes of motor units in reinnervated m.g. and l.g.s. muscles was similar to normal, both in terms of the muscle unit size (determined by measuring tetanic tension) and axon size (determined from the amplitude of the extracellularly recorded action potential). The amplitude of the axon potentials in the crossed nerves was weakly correlated with calculated conduction velocities because of the variation in the conduction delays across the suture line. As axon potential amplitude is a direct function of axon size at the recording site, it provided a reliable measure of regenerating axon size. Motor units were classified as slow (s.), fast fatigue resistant (f.r.), fast intermediate (f.i.) or fast fatigable (f.f.) by their contractile speed and fatigue properties. Tetanic tensions generally increased from slow to fast units with s. less than f.r. less than f.i. less than f.f. in reinnervated and normally innervated muscles, but the overlap between different unit types was considerably greater in reinnervated muscles. Thus, peripheral reorganization of nerve and muscle properties according to size can occur in reinnervated muscles, irrespective of the source of the regenerating nerves.

Action Potentials↗
PubMed1986

Meningitis caused by Streptococcus suis type II.

A 49 year old head porter developed meningitis shown to be caused by Streptococcus suis type II. The rare human infections with the organism, a pathogen of pigs, usually occur in those employed handling pig meat and are associated with auditory or vestibular dysfunction.

Animals↗
PubMed1986

Nonlinear stiffness--force relationships in whole mammalian skeletal muscles.

Small, sinusoidal length changes were superimposed on isometric contractions of fast- and slow-twitch mouse muscles, which were stimulated maximally via their nerves. Stiffness increased with increasing frequency of sinusoidal stimulation, but the relative time course of force and stiffness changes during twitch, tetanic, or partially fused contractions was quite invariant over a range of frequencies in both muscles. Typically, stiffness increases more rapidly than force during contraction and decreases less rapidly during relaxation. This pattern was observed at various temperatures and with various numbers of stimuli. It can be described by a nonlinear relation between stiffness and force with some hysteresis. The presence in the muscle of parallel and series elastic elements, whose stiffness varies with force, may account for the nonlinear relation. This nonlinearity can be used to relate the patterns for summation of force and stiffness observed with brief trains of stimuli under a variety of conditions.

Animals↗
PubMed1986

Granulocyte-mediated airway edema in guinea pigs.

To determine the role of polymorphonuclear leukocytes (PMNs) in the airway edema that accompanies airway inflammation, we studied the effects of a 1-h exposure to 2 ppm toluene diisocyanate (TDI) on tracheal extravasation of Evans blue dye and on the concentration of PMNs in the tracheal wall. Tracheal Evans blue content was significantly increased by TDI exposure (53.6 +/- 8.0 micrograms/g tracheal tissue (mean +/- SE) for animals exposed to TDI and 16.3 +/- 2.0 for animals exposed to air, P less than 0.0025) as were both the intravascular and extravascular concentration of PMNs in tracheal sections (intravascular PMNs were 28.0 +/- 8.4 X 10(3) cells/mm3 for TDI and 1.5 +/- 1.5 X 10(3) for air, P less than 0.025, extravascular PMNs were 10.9 +/- 4.5 X 10(3) for TDI and 0 for air, P less than 0.05). PMN depletion with vinblastine or with hydroxyurea abolished both the increase in tracheal Evans blue extravasation and the increase in the concentration of intravascular and extravascular PMNs in animals exposed to TDI. PMN depletion with hydroxyurea did not significantly inhibit the increase in tracheal Evans blue extravasation caused by intravenous histamine. Administration of donor PMNs to animals depleted of PMNs with hydroxyurea reconstituted the TDI-induced increase in tracheal Evans blue extravasation (80.4 +/- 17.3 micrograms/g tissue (mean +/- SE) in animals exposed to TDI vs. 21.3 +/- 2.9 in animals exposed to air, P less than 0.025) and in the intravascular concentration of PMNs in tracheal sections [18.5 +/- 3.4 X 10(3) cells/mm3 (mean +/- SE) in animals exposed to TDI vs. 1.3 +/- 1.3 X 10(3) in animals exposed to air, P less than 0.0025].(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Hydroxyurea inhibits airway hyperresponsiveness in guinea pigs by a granulocyte-independent mechanism.

Exposure of guinea pigs to toluene diisocyanate (TDI) causes an increase in airway responsiveness to inhaled acetylcholine. This increased airway responsiveness is temporally associated with an increase in polymorphonuclear leukocytes (PMN) in the tracheal wall. To determine whether PMN play a mechanistic role in this increase in acetylcholine responsiveness, we studied the effects of PMN depletion on this response with 2 different cytotoxic drugs, hydroxyurea and cyclophosphamide. Airway responsiveness was measured in untreated, hydroxyurea-treated, or cyclophosphamide-treated animals while they breathed spontaneously or during mechanical ventilation through a tracheostomy. In untreated animals, exposure to TDI caused a significant increase in airway responsiveness to acetylcholine for both spontaneously breathing and anesthetized and ventilated animals. This TDI-induced increase in airway responsiveness was associated with a significant influx of PMN into both the extravascular and intravascular trachea. Treatment with hydroxyurea, to reduce PMN counts in the bloodstream to less than 200/mm3, inhibited both the TDI-induced increase in airway responsiveness and the TDI-induced influx of PMN into the trachea of both spontaneously breathing and mechanically ventilated animals. In mechanically ventilated animals, treatment with cyclophosphamide, until PMN counts in the bloodstream were less than 200/mm3, also inhibited the influx of PMN into the trachea but did not inhibit the TDI-induced increase in airway responsiveness. These results suggest that PMN are not necessary for the TDI-induced increase in airway responsiveness and that hydroxyurea inhibits this effect by a mechanism other than PMN depletion.

Acetylcholine↗
PubMed1986

Capitation reimbursement for pediatric primary care.

A feasibility analysis of capitation reimbursement for a primarily Medicaid population in The Johns Hopkins Pediatric Primary Care Clinic was conducted. The utilization of all inpatient and outpatient care of 2,261 patients was monitored for a 6-month period. As a result, per capita rates based on charges were determined for each group of patients according to type of insurance. Blue Cross and private insurance patients had capitation rates three times that of the Medicaid patients and over ten times that of self-pay patients This variation in utilization was attributed to the selection of enrollees, the morbidity of the population, and the varying services covered by payor group. Administrative issues regarding establishing a pediatric health maintenance organization are also discussed. Close supervision of house staff in treating patients, including admissions, length of stay, and specialty referral is of utmost importance in containing costs in this clinic setting.

Capitation Fee↗
PubMed1986

Alcohol consumption and its relationship to smoking, weight, blood pressure, and blood lipids. The Albany Study.

Between 1953 and 1955, a still-ongoing prospective cardiovascular study enrolled 1,910 employed men. Men who drank more alcohol had higher levels of cigarette use, blood pressure, and high-density-lipoprotein cholesterol concentrations. After 18 years of follow-up, the survivors consumed twice as much alcohol, on the average, as they had at entry, weighed slightly more, and had substantially higher blood pressures. Formerly heavy drinkers who had quit, however, lost weight and had less than average blood pressure increases. There was no significant association between changes in smoking habits and changes in drinking habits.

Adult↗
PubMed1985

Drinking and coronary heart disease: the Albany Study.

The relation of alcohol consumption to coronary heart disease (CHD) was examined in a cohort of 1910 employed men aged 38 to 55 years enrolled in the Albany Study, a prospective investigation of factors related to cardiovascular disease. Two follow-up periods were examined, one between 1953-54 and 1971-72, the other after 1971-72. In the initial period, there was no clear evidence of a relation between the rate of alcohol consumption and CHD incidence. In the later period, men whose monthly consumption was 60 ounces or more had a lower than average CHD incidence rate. A negative relationship with drinking held for all manifestations of CHD. Other CHD risk factors were examined, special attention being given to cigarette smoking and HDL-cholesterol. The fact that drinking is a matter of choice may introduce some confounding factors. The absence of a relation between drinking and CHD risk in the earlier follow-up suggests the need for caution in interpreting the results.

Adult↗
PubMed1985

Temperature effects on the kinetics of force generation in normal and dystrophic mouse muscles.

The kinetics of isolated extensor digitorum longus and soleus muscles from normal and genetically dystrophic (129/ReJ dy/dy) mice were studied at temperatures from 8 to 38 degrees C. The rate constants for the exponential rise of tetanic force and for the exponential decay of force during an isometric twitch or short tetanus were similar in normal and dystrophic soleus muscles, but the decay rates were significantly reduced in dystrophic extensor digitorum longus muscles. The temperature dependence for several rate constants for isometric twitches and tetani was similar in all muscles studied, suggesting that the same rate limiting processes apply to fast and slow, normal and dystrophic muscles. Thus, the contractile proteins and those in the sarcoplasmic reticulum of dystrophic muscle are probably normal. The slower relaxation phase in dystrophic extensor digitorum longus muscles is compatible with a reduction in Ca2+-pumping sites in the sarcoplasmic reticulum, perhaps secondary to a change in motor unit composition. Some changes in the temperature dependence for measured times, toward those of soleus muscles, is consistent with the increased proportion of slow twitch motor units in dystrophic extensor digitorum longus muscles.

Animals↗
PubMed1985

The relation of drinking and smoking habits to diet: the Lipid Research Clinics Prevalence Study.

The relation of cigarette smoking and alcohol use to diet was examined in a general population of adults ages 20-59 years enrolled in the Lipid Research Clinics (LRC) Prevalence Study. There was a positive association between cigarette and alcohol use, but little relation between these habits and the nutrient intake. The total energy from food was about the same whether or not a person drank or smoked; alcohol was simply added to food intake. However, persons who drank received slightly less of their food energy from carbohydrate than persons who did not drink and persons who smoked received slightly more of their food energy from fat than did nonsmokers. Both persons who drank and persons who smoked weighed less than would be expected from their total energy intake. While these relationships were similar for men and women, among women they were stronger for those using gonadal hormones than among those not using these hormones.

Adult↗
PubMed1985

Lupus pernio: a clinico-radiological study of thirty-five cases.

Thirty-five patients with lupus pernio were observed in a series of 818 patients with clinical and histological evidence of sarcoidosis. This analysis provides the natural history of lupus pernio and its associated clinico-radiographic features. There was intrathoracic involvement in 74% of patients, upper respiratory tract disease in 54%, reticulo-endothelial involvement in 54%, bone cysts in 43% and ocular lesions in 37%. It predominated in West Indies-born women. Histological confirmation was easily obtained by nasal mucosal biopsy and this could be repeated serially to evaluate the response to various treatments. Nasal bone radiographs showed destruction of the nasal bones, porosis and alteration in bone texture. Peripheral bone cysts were evident in 50% of patients who were radiographed, and in about 50% of these patients, the cysts were found in both hands and feet.

Adult↗
PubMed1985

Airway hyperresponsiveness and inflammation induced by toluene diisocyanate in guinea pigs.

We examined the changes in airway responsiveness to increasing doses of an acetylcholine aerosol in anesthetized and ventilated guinea pigs 2, 6, or 24 h after exposure to 2 ppm toluene diisocyanate (TDI) or 2 h after exposure to air or 1 ppm TDI. Pulmonary resistance (RL) after the animals inhaled a buffered saline aerosol was used as baseline and was similar for air and TDI groups. The concentration of acetylcholine calculated to cause a 200% increase in RL was significantly lower for animals studied at 2 h (0.68%) or at 6 h (0.77%), but not at 24 h (2.39%), after TDI than for air animals (3.07%). The increase in airway responsiveness in the TDI-exposed animals was associated with histologic changes in the trachea and intrapulmonary airways. Exposure to 2 ppm TDI caused a patchy loss of cilia, shedding of epithelial cells into the airway lumen, and an influx of inflammatory cells into the trachea and other airways. In the lamina propria of the trachea, the concentration of extravascular polymorphonuclear leukocytes (PMN) was 13- to 26-fold greater in animals studied 2 or 6 h after exposure to 2 ppm TDI or at 2 h after 1 ppm TDI than in animals exposed to air. The concentration of PMN in the epithelium was significantly increased only in animals examined 2 h after 2 ppm TDI. Exposure to TDI also caused an influx of eosinophils into the tracheal mucosa. This influx occurred later and was more persistent than the influx of PMN. These results indicate that a single exposure to TDI can cause an increase in airway responsiveness that is associated with epithelial injury and acute airway inflammation.

Acetylcholine↗
PubMed1985

Iron pigment in the brain of a man with tardive dyskinesia.

A 64-year-old man with bipolar affective disorder developed persistent tardive dyskinesia following an overdose of lithium and haloperidol. Two years later he died of unknown causes. Neuropathologic examination revealed extensive deposition of iron in basal ganglia and substantia nigra.

Basal Ganglia↗