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Biomedical subjects

M Johnson

Publications and source records attributed to M Johnson.

At least 451 records · Page 25Linked to original sources
PubMed1994

The relationship among television watching, physical activity, and body composition of young children.

PURPOSE: Television watching has been reported to be associated with obesity, resting energy expenditure, and lower daily physical activity among both children and adolescents. However, most of these studies were based on self report or data collected in laboratory settings. This study examined the relationship among observed time of television watching, observed physical activity level and body composition among 3- or 4-year-old children. METHODS: African-American (41.4%), Mexican-American (23%), and Anglo-American (35.6%) children (N = 191, males = 90) from the Texas site of the Studies of Child Activity and Nutrition program were observed from 6 to 12 hours per day up to 4 days over 1 year. Activity level each minute of the day was measured with the Children's Activity Rating Scale (interobserver reliability = .84 +/- .001). The interobserver reliability of time of television watching was .96 +/- .08. RESULTS: The median of the longest number of consecutive minutes of television watching was 15 (range = 1 to 79). The median percent of minutes of television watching of total observed minutes was 14.8% (0% to 58%) and the median percent of minutes of inside minutes was 17.9% (0% to 80.9%). There were no gender or ethnic differences in time watching television or physical activity during television watching. Physical activity during television watching was lowest during the longest bout of television watching (mean = 1.48 +/- .28) compared to outside minutes (mean = 2.38 +/- .21), inside non-television minutes (mean = 1.96 +/- .13) and inside television minutes (mean = 1.65 +/- .18). The level of physical activity during television-watching times was highest (P < .0031) during October and November and lowest during March, April, June, and July. Longest bout of television watching and percent of minutes watching television to total observed minutes were inversely associated with mean physical activity, percent of minutes of physical activity levels 3, 4, or 5, and percent of physical activity levels 4 or 5. Percent of television watching to inside minutes was negatively correlated with physical activity levels 4 or 5. Television-watching behavior was not associated with body composition. CONCLUSIONS: Television watching was weakly negatively correlated with physical activity levels, and physical activity was lower during television-watching than non-television-watching time in this sample of children. Television viewing behavior was not associated with body composition.

Black or African American↗
PubMed1994

Sensory perception of patients on selected antineoplastic chemotherapy protocols.

Antineoplastic chemotherapy (ANCT) is a primary and adjuvant treatment modality for cancer. Although researchers have found that patients who are given preparatory sensory information before various health-care procedures experience less discomfort, literature describing subject's sensory experience before, during, and after ANCT is lacking. The purpose of this study was to elicit sensory responses from subjects before, during, and after one of six cycles of their initial course of treatment on one of two emetogenic ANCT protocols. These descriptions will be used to develop a preparatory sensory nursing intervention that may promote self-care and help cancer patients cope with the distress of chemotherapy. The Sensory Information Questionnaire was administered to a sample of 44 subjects who had just completed a cycle of ANCT. Subjects provided descriptors of all senses. The senses for which subjects most frequently provided descriptors were taste, touch, and smell. Descriptors varied for some sensations according to the chemotherapy drug protocols.

Adaptation, Psychological↗
PubMed1993

Effects of nimodipine on the amphetamine- and methamphetamine-induced decrease in tryptophan hydroxylase activity.

The effects of nimodipine on the amphetamine- and methamphetamine-induced decrease in central tryptophan hydroxylase activity was examined. Rats were administered 4 or 5 injections of amphetamine or methamphetamine at 6-h intervals with or without nimodipine (1 mg/kg), and killed 1 or 18 h after the last drug administration. The decrease in hippocampal tryptophan hydroxylase activity induced by amphetamine and methamphetamine was potentiated by the administration of nimodipine. Moreover, while hippocampal tryptophan hydroxylase activity was not altered by 2.5 mg/kg methamphetamine alone, the coadministration of 1 mg/kg nimodipine decreased the enzymatic activity to 68% of control. The decrease in striatal tryptophan hydroxylase activity caused by these amphetamine analogues was not significantly altered by the coadministration of nimodipine. Interestingly, nimodipine increased hippocampal and striatal amphetamine concentrations to 187 and 162%, respectively, of the concentrations measured in animals treated with amphetamine alone. Nimodipine also increased by 2-fold the plasma concentration of methamphetamine and amphetamine measured 3 h after a single administration of methamphetamine, whereas the hippocampal concentrations of these compounds were raised to 354 and 516%, respectively, of that in animals treated with methamphetamine alone. These results suggest that nimodipine altered drug distribution and potentiated the methamphetamine-induced decrease in hippocampal tryptophan hydroxylase activity by increasing the cerebral methamphetamine concentration.

Amphetamine↗
PubMed1993

Autoradiographic distribution of binding sites for the non-NMDA receptor antagonist [3H]CNQX in human motor cortex, brainstem and spinal cord.

The distribution of non-NMDA receptors in the normal human motor cortex, brainstem and spinal cord has been investigated using [3H]CNQX. In the motor and premotor cortex, specific [3H]CNQX binding was present in all cortical laminae with the highest density of binding sites in laminae I, II and the upper part of III. In the normal brainstem, non-NMDA receptors labelled by [3H]CNQX had a heterogeneous distribution. Brainstem motor nuclei subserving eye movements, which tend to be spared in motor neuron disease (MND), had a higher density of [3H]CNQX binding sites compared to other cranial nerve motor nuclei (VII, X, XII) which tend to be affected. Specific [3H]CNQX binding was present throughout the spinal grey matter, the greatest density of binding being found in the substantia gelatinosa. Excitotoxicity at non-NMDA receptors has been implicated in chronic neurodegenerative diseases such as motor neuron disease. This study suggests that the density of non-NMDA receptors, labelled by [3H]CNQX, does not account for selective vulnerability of motor neurons in this disorder.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1993

Blockade of tachykinin NK1 receptors by CP-96345 enhances dopamine release and the striatal dopamine effects of methamphetamine in rats.

The nonpeptide, tachykinin NK1 receptor antagonist, CP-96345, permits the study of the physiological role of extrapyramidal substance P systems. Using microdialysis, we observed that locally applied CP-96345 (200 nM) caused a significant increase in dopamine release in the striatum as well as substantially enhancing striatal dopamine release caused by a low dose of methamphetamine (0.5 mg/kg s.c.). In addition, multiple systemic administrations of CP-96345 almost doubled the dopamine-mediated responses of the striatal neurotensin and dynorphin systems to high doses of methamphetamine (10 mg/kg/dose s.c.). Our findings suggest that the physiological role of substance P released in the striatum is to decrease the activity of the nigrostriatal dopamine pathway.

Animals↗
PubMed1993

Transmitters in the developing and senescent human brain.

During development and throughout adult life, modeling of CNS structure and function occurs as a result of experience. Transmitters play a central role in this mechanism both directly and indirectly (through control of neurotrophin expression) by governing synapse formation, elimination or consolidation. Cholinergic and excitatory amino acid transmitter system activities have been examined in postmortem human brain obtained from normal individuals varying from the prenatal period to old age. Whereas glutamate NMDA receptor binding (measured using MK801) was not substantially altered across the postnatal period, dramatic and differing patterns of choline acetyltransferase (ChAT) activity were evident. Thus, in the cerebellum, ChAT activity was 10-fold higher in fetal compared to adult individuals whereas in the hippocampus there was little or no activity in the fetus and activity rose postnatally to reach a maximum in middle age and then declined to half that level by the tenth decade. Acetylcholinesterase (AChE) histochemical reactivity paralleled the developmental pattern for ChAT in the hippocampus and adjacent cortex with respect to fiber reactivity. These findings indicate that cholinergic synaptic plasticity may be restricted to the prenatal period in cerebellum but occur in both the postnatal period and throughout adult life in the hippocampus and cortex, a concept consistent with the temporal and regional expression of cholinoneurotrophins (NGF and related peptides). Vulnerability of the hippocampus and cortex to age-related pathology such as beta-amyloidosis and neuritic plaque formation may relate to the extended period of cholinergic synaptic sculpting in these areas.

Adult↗
PubMed1993

Ceruloplasmin levels in the human superior temporal gyrus in aging and Alzheimer's disease.

In the present study we observed a loss in excess of 1/3 of the copper transport and anti-oxidant protein ceruloplasmin in both the gray and white matter from superior temporal gyrus in Alzheimer's diseased brains compared to age-matched controls. A decrease in ceruloplasmin could be reflected in decreased cellular metabolic processes such as the electron transport system and a decrease in the ability of the brain to protect itself from oxidative damage. Both decreased metabolic activity and an increase in oxidative insults are known to be associated with the neurological events in Alzheimer's disease, but the mechanism by which these phenomena occur are unknown. These results coupled with previous reports from this laboratory on iron regulatory proteins in the brain suggests one way in which cellular dysfunction and oxidative stress occurs in AD may be through a loss of ability to maintain a balance of essential metals.

Aged↗
PubMed1993

Effects of ritanserin on the 3,4-methylenedioxymethamphetamine-induced decrease in striatal serotonin concentration and on the increase in striatal neurotensin and dynorphin A concentrations.

The concentration of serotonin (5-HT) measured in rat striatum was reduced to 75% of control 1 week after a single subcutaneous administration of dl-3,4-methylenedioxymethamphetamine (MDMA, 20 mg/kg). This decrease was prevented by pretreating the animals with ritanserin. Eighteen hours after MDMA (20 mg/kg), striatal concentrations of neurotensin-like immunoreactivity (NTLI) and of dynorphin A-like immunoreactivity (DLI) were increased to 250 and 487% of control, respectively, but ritanserin failed to prevent these changes. This study supports a role for 5-HT2 receptors in the mechanism by which a single high dose of MDMA induces neuronal damage to the serotonergic system, but not the MDMA-induced increase in central NTLI and DLI concentrations.

3,4-Methylenedioxyamphetamine↗
PubMed1993

Regional patterns of cholinergic and glutamate activity in the developing and aging human brain.

The levels of choline acetyltransferase (ChAT) and the binding activity of N-methyl-D-aspartate (NMDA) and non-NMDA receptors have been measured in the hippocampus, entorhinal cortex, frontal cortex and cerebellum, in a series of human brains from 24 weeks gestation to 100 years. The patterns of ChAT and glutamate receptor activity during aging and development were strikingly different in the different brain areas. In the hippocampus and associated cortex, ChAT activity did not reach a peak until middle age, when it almost immediately started to decline by 50-60% to the 10th decade, whereas in the frontal cortex ChAT peaked transiently in the infant and then stayed constant during aging. In the cerebellum ChAT activity was very high in the foetus and fell in the neonate to maintain a constant level more in line with the concentrations found in the other brain areas through the rest of life. The high levels of ChAT in the foetal cerebellum were not associated with high acetylcholinesterase (AChE) content, which tended to increase during development, and was present initially in Purkinje cells (foetus and neonate) and the molecular layer in the adult. In the hippocampus and entorhinal cortex, autoradiographic [3H]MK-801 binding was relatively constant throughout life, however, [3H]CNQX binding rose from the perinatal period up to a peak in the 1st or 2nd decade and then tended to fall with age. In the cerebellum, autoradiographic binding of both ligands rose from the foetal period to reach a plateau by the age of 10 years and there was no apparent further change during aging. These data on cholinergic and glutamatergic phenotypic changes during development and senescence reflect marked variations in regional plasticity and aging within and between the two transmitter systems and are likely to contribute to our understanding of their role in the different brain areas investigated.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1993

Autoradiographic comparison of the distribution of [3H]MK801 and [3H]CNQX in the human cerebellum during development and aging.

The autoradiographic distribution of N-methyl-D-aspartate (NMDA) and D,L-a-amino-3-hydroxyl-5-methyl-4-isoxazoleproprionic acid/quisqualate (AMPA/QUIS) receptors was determined in cerebellum obtained at autopsy from 37 human individuals, aged from 24 weeks gestation to 95 years. [3H]MK801 was used to label the NMDA receptor and [3H]CNQX to label the AMPA/QUIS receptor. AMPA/QUIS receptors were concentrated in the cerebellar molecular layer, and NMDA receptors in the granular layer. Significant (3- to 4-fold) increases in binding were seen for both ligands from the fetal to neonatal periods in the molecular layer (CNQX) and in both molecular and granular layers (MK801). MK801 binding in the molecular layer continued to increase with age up to the tenth decade and together with binding in the granular layer, increased 2-fold between 10-40 years. The Purkinje cell layer was negative for MK801 binding until the 6-7th decade when it became positive. [3H]CNQX binding in the molecular layer increased significantly with age between the fetal period and the tenth decade, whereas in the granular layer binding increased from neonate to 40 years, but then decreased significantly from 60 years to the tenth decade. Lamination of the molecular and granular layers was absent during the fetal period and appeared with both ligands during the neonatal period. These marked differences in age-related expression of ligand binding sites in the granular layer during development and aging are of potential significance in relation both to selective vulnerability to ischemia, and synaptic plasticity and remodelling related to neuronal loss in senescence.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1993

Radial or ulnar artery laceration. Repair or ligate?

OBJECTIVE: To determine the relationship between patency of radial or ulnar artery repair and later hand symptoms. DESIGN: Call-back survey. SETTING: Urban trauma center. PATIENTS: Thirty-two subjects with wrist artery lacerations undergoing 26 arterial repairs and six artery ligations during an 8-year period. INTERVENTIONS: Directed history and hand examination (palpation of wrist pulses, Doppler Allen test, and Doppler interrogation of palmar arch and digital vessels). MAIN OUTCOME MEASURES: History of hand claudication, weakness, or cold sensitivity or paresthesias and patency of wrist arteries. RESULTS: Twelve (46%) of 26 wrist artery repairs were patent. There was no evident benefit of optical magnification or specialization in hand or vascular surgery. No subjects had hand claudication; there was a 50% incidence of hand weakness and a 12% incidence of cold sensitivity independent of patency of the damaged wrist artery and present only in subjects with associated nerve injury. Professional charges for wrist artery repair were threefold to fourfold higher than those for wrist artery ligation. CONCLUSION: Consonant with prior reports, patency following repair of radial or ulnar artery laceration does not exceed 50%. Later hand symptoms relate to nerve or tendon damage, not to arterial patency. In the absence of acute hand ischemia, simple ligation of a lacerated radial or ulnar artery is safe and cost-effective.

Adolescent↗
PubMed1993

Autoradiographic comparison of cholinergic and other transmitter receptors in the normal human hippocampus.

The vulnerability of the human hippocampal complex to disease, trauma, and aging indicates the necessity to target this area therapeutically. The distribution and density of transmitter receptors provide a rational basis for this approach, and in this study the topography of 11 different pharmacological sites is compared with the cholinergic innervation, which is particularly vulnerable in dementia. The regional distribution of cholinergic innervation to the normal adult human hippocampus and adjacent cortex, marked by acetylcholinesterase (AChE) fiber and terminal reactivity, is notable for its concentration in CA2/3 of Ammon's horn and the dentate fascia. Neither nicotinic (high-affinity nicotine binding) nor muscarinic ("M1" or "M2") cholinergic receptor binding paralleled this distribution. In Ammon's horn, 5-HT2 and kainate receptor binding more closely resembled the pattern of AChE, being concentrated in CA2-4 compared with CA1. By contrast, muscarinic M1 and M2, 5-HT1A, benzodiazepine (including zolpidem-insensitive binding), NMDA (MK801), and AMPA/QUIS receptors were higher in CA1 and/or subiculum. Kainate binding, like AChE, was high in CA4. 5-HT2 and nicotinic binding partially mimicked the pattern of AChE around the granule layer. In the subicular complex and parahippocampal gyrus, where cholinergic activity is relatively lower, muscarinic, 5-HT1A, and benzodiazepine binding were relatively high and the nicotinic receptor was remarkable for its highest density compared to other areas examined. In stratum lacunosum-moleculare of CA1, which was relatively low in AChE activity, there was a dense band of nicotinic, M2, and benzodiazepine receptor binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1993

Transitional objects, pre-sleep rituals, and psychopathology.

The prevalence among college age adults (N = 184) of transitional objects and pre-sleep preparation rituals and their relationship to mental health was investigated. Two scales concerning use of transitional objects and fear of going to sleep, showed statistically significant correlations with self-reports of nightmares, loneliness, depression, and previous physical and sexual abuse. Forty-six students scoring in the highest 15% of the distribution of scores for each scale were compared with students in the lowest 15% on the MAACL and SCL-90-R. High scoring students showed significantly higher levels of depression, anxiety, hostility, and interpersonal sensitivity.

Adult↗
PubMed1993

Physician advice to quit smoking: results from the 1990 California Tobacco Survey.

OBJECTIVE: To estimate the percentage of California smokers who visit physicians each year and thus determine the extent of the opportunity for physicians to advise their smoking patients to quit; to identify sociodemographic and other characteristics related to smokers' reporting that advice was given; and to look for evidence that physician advice influences quitting behavior. SETTING AND DESIGN: Data were collected as part of the 1990 California Tobacco Survey, a large (n = 24,296) population-based telephone survey. PARTICIPANTS: 9,796 current smokers, including 5,559 daily smokers who had visited a physician in the preceding year. MEASUREMENTS AND MAIN RESULTS: Two-thirds of all smokers had visited a physician in the year before the interview, but only about 50% of Hispanic and Asian smokers had done so. Multivariate analysis showed that advice at the last visit was independently related to older age, higher cigarette consumption, and poorer perceived health. Compared with smokers never advised to quite by a physician, those advised to quit at the last visit were 1.61 (95% confidence interval, 1.31-1.98) times more likely to report a quit attempt in the preceding year and 1.90 (95% confidence interval, 1.45-2.48) times more likely to be preparing to quit; however, those advised previously but not at the last visit showed no more quitting activity than did smokers never advised to quit. CONCLUSION: Physicians have considerable opportunity to reach all demographic subgroups of the population, but the nature of the subgroups advised most (those who are older, have high consumption of cigarettes, or have poor health) suggests that physicians tend to treat such advice as a therapeutic rather than a preventive intervention. Physician advice at the most recent visit encourages patients to think about quitting and probably leads to quit attempts. Thus, it is vital that physicians perform the simple intervention of advising every smoker to quit at every visit.

Adolescent↗
PubMed1993

The pharmacology of salmeterol.

Salmeterol was developed to provide prolonged bronchodilatation to control nocturnal symptoms and improve maintenance therapy in asthmatic patients. Salmeterol is > 10,000 times more lipophilic than salbutamol and has greater affinity for the beta 2-adrenoceptor. Membrane binding is non-competitive and dissociation is slow so that its effects last for many hours. Despite this, salmeterol does not accumulate in tissues. Its mechanism of action can be explained by binding to a specific exo-site domain of the beta 2-receptor protein to produce continuous stimulation of the active site of the receptor, which gives salmeterol a profile of pharmacological activity unlike that of other beta 2-agonists. Due to its potent and prolonged activation of beta 2-adrenoceptors in airway smooth muscle cells, endothelial cells, mast cells and epithelial cells, salmeterol induces prolonged bronchodilatation, reduced vascular permeability, inhibition of inflammatory mediators, stimulation of ciliary function and modulation of ion and water transport across the bronchial mucosa.

Adrenergic beta-Agonists↗
PubMed1993

Case report: accumulation of 99mTc-hydroxymethylene diphosphonate by liver metastases of prostatic adenocarcinoma.

We describe the case of a man with known prostatic carcinoma and bone metastases who was admitted with jaundice and hepatomegaly. A bone scan showed uptake of diphosphonate by the liver and ultrasound suggested the presence of diffuse metastatic disease. Liver biopsy revealed foci of carcinoma cells in the portal tracts which exhibited positive cytoplasmic staining for prostate-specific antigen, thus confirming the presence of metastatic prostatic adenocarcinoma.

Adenocarcinoma↗