Search PubMed⌕ Search

Biomedical subjects

A Roy

Publications and source records attributed to A Roy.

At least 91 records · Page 5Linked to original sources
PubMed2001

Childhood trauma and suicidal behavior in male cocaine dependent patients.

A consecutive series of 100 male cocaine dependent patients were interviewed about suicidal behavior and completed the 34-item Childhood Trauma Questionnaire (CTQ) to determine whether childhood trauma is associated with suicidal behavior in cocaine dependent men. Patients who had attempted suicide (n = 34) reported significantly higher scores for childhood emotional abuse, physical abuse, sexual abuse, and emotional and physical neglect than patients who had never attempted suicide (n = 66). In this study, various childhood traumas were found to be significantly associated withsuicidal behavior among adult male cocaine dependent patients.

Adult↗
PubMed2001

Identification and initial characterization of spore-like cells in adult mammals.

We describe the identification and initial characterization of a novel cell type that seems to be present in all tissues. To date we have isolated what we term "spore-like cells" based on the characteristics described below. They are extremely small, in the range of less than 5 microm, and appear to lie dormant and to be dispersed throughout the parenchyma of virtually every tissue in the body. Being dormant, they survive in extremely low oxygen environments, as evidenced by their viability in tissues (even in metabolically very active tissues such as the brain or spinal cord) for several days after sacrifice of an animal without delivery of oxygen or nutrients. The spore-like cells described in this report have an exceptional ability to survive in hostile conditions, known to be detrimental to mammalian cells, including extremes of temperature. Spore-like cells remain viable in unprepared tissue, frozen at -86 degrees C (using no special preservation techniques) and then thawed, or heated to 85 degrees C for more than 30 min. Preliminary characterization of these cells utilizing basic and special stains, as well as scanning and transmission electron microscopy reveal very small undifferentiated cells, which contain predominantly nucleus within a small amount of cytoplasm and a few mitochondria. Focal periodic acid-Schiff and mucicarmine stains suggest a coating of glycolipid and mucopolysaccharide. In vitro, these structures have the capacity to enlarge, develop, and differentiate into cell types expressing characteristics appropriate to the tissue environment from which they were initially isolated. We believe that these unique cells lie dormant until activated by injury or disease, and that they have the potential to regenerate tissues lost to disease or damage.

Animals↗
PubMed2001

Effects of chronic ethanol intake and its withdrawal on the expression and phosphorylation of the creb gene transcription factor in rat cortex.

This investigation examined the effects of chronic ethanol treatment (15 days) and its withdrawal (24 h) on the expression and phosphorylation of cyclic AMP-response element-binding (CREB) protein in the rat cortex. The effects of chronic ethanol treatment and withdrawal on protein kinase A (PKA) activity and on the expression of the regulatory RII-beta- and the alpha-subtype catalytic subunits of PKA, and on the protein expression of Ca(2+)/calmodulin-dependent protein kinase IV (CaM kinase IV) and calcineurin in the rat cortex were also investigated. It was found that ethanol withdrawal but not ethanol treatment produced a significant decrease in the phosphorylated CREB (p-CREB) and CaM kinase IV protein levels in the frontal, parietal, and piriform cortex. Ethanol treatment and its withdrawal had no effect on the protein levels of total CREB in the frontal, parietal, and piriform cortex. On the other hand, ethanol treatment produced a significant reduction in the protein levels of CREB, p-CREB, and CaM kinase IV in the cingulate gyrus, and these changes reverted to normal levels during ethanol withdrawal. Total CREB protein levels were significantly higher in the cingulate gyrus during ethanol withdrawal. It was also observed that mRNA levels of CREB were significantly higher in the rat cortex during ethanol withdrawal but not during ethanol treatment. The protein levels of RII-beta- and alpha-subtype catalytic subunits of PKA and PKA activity were not modified in the rat cortex by chronic ethanol treatment and its withdrawal. Furthermore, the expression of calcineurin in the rat cortex was not altered during ethanol treatment and withdrawal. Taken together, these results suggest the possibility that decreased CREB-dependent events in the neurocircuitry of the frontal, parietal, and piriform cortex may play an important role in the phenomenon of alcohol dependence and also that decreased CREB-dependent events in the neurocircuitry of the cingulate gyrus may play a role in alcohol tolerance.

Animals↗
PubMed2001

Progression to 100% off-pump coronary artery bypass with the Octopus 1 dual holder.

BACKGROUND: Can off-pump coronary artery bypass grafting become the routine standard in all elective primary coronary artery bypass grafting (CABG) operations? This paper shows how this aim has been achieved during one year in 130 off-pump cases performed through a sternotomy. This strategy allows for full revascularization (up to six grafts) without the disadvantage of cardiopulmonary bypass. The study introduces a variant of the Octopus stabilizer, a single Octopus 1 arm (Medtronic, Inc., Minneapolis, MN) with a dual holder. MATERIALS AND METHODS: From November 1998 through February 2000, 130 patients underwent coronary artery bypass grafting through a sternotomy off-pump utilizing a stabilizer and CO2 blower. The stabilizer most frequently used to achieve this was a single Octopus 1 arm equipped with a dual holder to accommodate two straight suction pods. The holder allowed increased flexibility and manipulation of the suction pods with an equivalent of seven degrees' freedom of motion at the dual holder junction. Techniques for carrying out total revascularization are discussed. The progress of proportion of elective primary CABG revascularization performed off-pump is shown and results are compared with published reviews of the literature for off-pump coronary revascularization. RESULTS: Patient demographics included: age range 32 to 87, mean 61.3; female sex: 17%; ejection fraction < 50%: 54%; presence of left main stem disease: 17%. Overall Parsonnet risk score ranged 0-31, with a mean of 8.8. Graft numbers carried out were: 34 x 2, 34 x 3, 32 x 4, 25 x 5 and 5 x 6 anastomoses respectively. The mean number of distal anastomoses was 3.6 +/- 1.0. There was extensive coverage of the lateral aspect of the heart (153 circumflex territory grafts, 33%). Radial artery, left internal mammary artery or saphenous vein sequential (jump) grafts were used in 26 cases (20%). Apart from general experience, the use of the dual holder and wide opening of the right pleura were the two important factors allowing freedom for multi-vessel lateral and posterior wall grafting. Thirteen Genzyme (Genzyme Surgical Products, Inc., Cambridge, MA) and ten Octopus 2 (or 2+) stabilizers were used, mostly for two or three grafts. The remainder were carried out using the Octopus 1 (dual holder: 83). In the first three-month period, 31% of cases were off-pump compared to the last three-month period, when 96% were off-pump. In the last two months we performed 100% of all 27 cases referred off-pump. There were no deaths, strokes or myocardial infarctions. Ventricular arrhythmia occurred in two cases. Conversions to bypass were undertaken twice. Two unexpected renal failures occurred, neither of which were from the 13 patients with preoperative incipient renal failure, of whom none suffered a rise in postoperative creatinine of greater than 30%. The results compare favorably with published results despite having a large mean number of grafts of 3.6. CONCLUSION: Off-pump surgery with full revascularization has now become feasible for all primary elective coronary artery graft operations.

Adult↗
PubMed2001

Epidemiologic investigations of a malaria outbreak in northern Delhi area.

Epidemiologic investigations revealed a 56.7 and 13.32% slide positivity rate in febrile and afebrile malaria cases, respectively. In both cases, Plasmodium falciparum was predominant. Anopheles culicifacies resistant to dichlorodiphenyltrichloroethane and benzene hexachloride (hexachlorocyclohexane) was found breeding profusely in pools and ponds created by excavation of earth around brick kiln in the region. Furthermore, children were not found to be producing significant levels of antibodies and a large percentage of patients harbored chloroquine-resistant parasites. Also, more than 1 P. falciparum strain was present in the population. We detected 2 strains, VI and VII, of which type VI was predominant.

Adolescent↗
PubMed2000

Mice lacking in gp91 phox subunit of NAD(P)H oxidase showed glomus cell [Ca(2+)](i) and respiratory responses to hypoxia.

The hypothesis that NAD(P)H oxidase may serve as an oxygen sensor was tested using the mice deficient (knock-out) in gp91phox subunit of NAD(P)H oxidase enzyme complex and compared with wild-type (C57BL/6J) strain measuring the ventilatory and glomus cell intracellular calcium ([Ca(2+)](i)) responses of carotid body to hypoxia. The hypoxic ventilatory responses as well as the [Ca(2+)](i) were preserved in the NAD(P)H oxidase knock-out mice. NAD(P)H oxidase, though a major source of oxygen radical production, is not the oxygen sensor in mice carotid body.

Animals↗
PubMed2000

Attention modulates synchronized neuronal firing in primate somatosensory cortex.

A potentially powerful information processing strategy in the brain is to take advantage of the temporal structure of neuronal spike trains. An increase in synchrony within the neural representation of an object or location increases the efficacy of that neural representation at the next synaptic stage in the brain; thus, increasing synchrony is a candidate for the neural correlate of attentional selection. We investigated the synchronous firing of pairs of neurons in the secondary somatosensory cortex (SII) of three monkeys trained to switch attention between a visual task and a tactile discrimination task. We found that most neuron pairs in SII cortex fired synchronously and, furthermore, that the degree of synchrony was affected by the monkey's attentional state. In the monkey performing the most difficult task, 35% of neuron pairs that fired synchronously changed their degree of synchrony when the monkey switched attention between the tactile and visual tasks. Synchrony increased in 80% and decreased in 20% of neuron pairs affected by attention.

Action Potentials↗
PubMed2000

Synthetic studies of the formation of oxazoles and isoxazoles from N-acetoacetyl derivatives: scope and limitations

[reaction: see text] The preparation of two types of heterocycles, oxazoles and isoxazoles, were achieved in good yields in a rapid and simple way by using N-acetoacetyl derivatives. Steric and electronic effects caused by the nature of the substituents at C1, C2, and C3 were studied. The best results were obtained with a chiral oxazolidinone moiety on C1 derived from (1R,2S)-(-)-norephedrine.

Journal Article↗
PubMed2000

The metabolic hypothesis revisited.

High levels of CO are used to mimic the stimulatory response of the CSN initiated by hypoxia. Using light of different wavelengths we show that the stimulatory effects of high CO can be pinpointed to the cytochrome c oxidase in the mitochondrial respiratory chain. This supports the metabolic theory of oxygen sensing in the mitochondria.

Animals↗
PubMed2000

Effects of 2,4-dinitrophenol (DNP) on the relationship between the chemosensory activities of the rat carotid body and the intracellular calcium of glomus cells.

To test the hypothesis that the uncoupler 2,4-dinitrophenol (DNP) increases [Ca2+]i equally well, independent of pHi, we studied the effects of 250 microM DNP on [Ca2+]i and carotid sinus nerve (CSN) activity of rat carotid body (CB). CSN activity was measured in CB perfused and superfused with hypocapnic (pHo 7.80) and normocapnic (pHo 7.42) Tyrode solutions. [Ca2+]i of glomus (type I cells) was assessed by superfusion techniques under identical conditions as for CSN recording experiments. The results indicate that 250 microM DNP increased [Ca2+]i of type I cells as well as CSN activity at both pHos, although alkalosis diminished these responses. Given that pHi will change with pHo, DNP did not make any additional pHi change, although [Ca2+]i changed. We conclude that DNP effects were due to [Ca2+]i change alone, and the relationship between [Ca2+]i and CSN activity are internally consistent.

2,4-Dinitrophenol↗
PubMed2000

Motor unit synchronization in young and elderly adults.

In an effort to determine whether aging might alter the manner in which pairs of motor units are coactivated, the extent of motor unit synchronization was assessed in the first dorsal interosseous (FDI) muscle in seven young (mean 28 years) and eight older adults (mean 75 years). During constant-force isometric contractions at either 50% or 100% of maximal effort, motor units were recorded using a four-wire needle electrode and a multi-channel recording technique. Customized software was utilized to identify the occurrences of motor unit action potentials from the resultant three-channel signals. The magnitude of motor unit synchronization was determined using six variables that have been described previously in the literature. The extent of motor unit synchronization was similar in both young and older adults, occurring in nearly every motor unit pair observed. During the 50% maximum voluntary contractions, the CIS synchronization measure (the number of synchronized discharges per unit time) averaged 2.5 in the young subjects and 2.4 in the older individuals. The intensity of motor unit synchronization was somewhat greater during maximal force isometric contractions. We conclude that motor unit synchronization in the FDI muscle is a ubiquitous phenomenon that is not affected by the aging process.

Action Potentials↗
PubMed2000

P(O(2))-P(CO(2)) stimulus interaction in [Ca(2+)](i) and CSN activity in the adult rat carotid body.

Since glomus cell intracellular calcium ([Ca(2+)](i)) plays a key role in generating carotid sinus nerve (CSN) discharge, we hypothesized that glomus cell [Ca(2+)](i) would correspond to CSN discharge rates during P(O(2))-P(CO(2)) stimulus interaction in adult rat carotid body (CB). Accordingly, we measured steady state P(O(2))-P(CO(2)) interaction in CSN discharge rates during hypocapnia (P(CO(2))=8-10 Torr), normocapnia (P(CO(2))=33-35 Torr) and hypercapnia (P(CO(2))=68-70 Torr) in normoxia (P(O(2)) approximately 130 Torr) and hypoxia (P(O(2)) approximately 36 Torr). The results showed P(O(2))-P(CO(2)) stimulus interaction in CSN responses. [Ca(2+)](i) levels were measured in isolated type I cells (2-3 cells/field), using Ca(2+) sensitive fluoroprobe indo-1AM. The [Ca(2+)](i) responses increased with increasing P(CO(2)) in normoxia. In hypoxia, [Ca(2+)](i) did not increase during hypocapnia but increased during normocapnia, showing P(O(2))-P(CO(2)) interaction. However, CSN response during hypoxia was far greater than that for [Ca(2+)](i) response, particularly during hypocapnic hypoxia. Thus, the [Ca(2+)](i) interaction cannot account for the whole CSN interaction. The origin of this CSN P(O(2)-)P(CO(2)) interaction must have occurred in part beyond cellular [Ca(2+)](i) interaction. Interactions at both sites (glomus cell membrane and sinus nerve endings) are reminiscent of reversible O(2)-heme protein reaction with a Bohr effect.

Animals↗
PubMed2000

Further evidence for low serum cholesterol and suicidal behaviour.

OBJECTIVE: To examine for a relationship between serum cholesterol and suicidal behavior. METHODS: Patients admitted after an overdose (N=120) were compared with controls (N=120) for their serum cholesterol levels. RESULTS: Patients who had overdosed had significantly lower serum cholesterol levels than controls (mean+/-S.D. 171+/-31 vs. 196+/-30 mg/dl, P<0.0001). CONCLUSION: These results add to a grouping literature reporting that low serum cholesterol is associated with suicidal behavior.

Adult↗
PubMed2000

Nitrite inhalants spontaneously liberate nitric oxide, which is not responsible for the immunotoxicity in C57BL/6 mice.

Nitrite inhalant abuse has been correlated epidemiologically with HIV seropositivity and with Kaposi's sarcoma. Using a mouse model, we have shown that inhaled isobutyl nitrite caused anemia and severely depressed immunity. In the present study, we showed that both isobutyl and cyclohexyl nitrites in air liberated nitric oxide (NO). An immunotoxic dose of 900 ppm isobutyl nitrite liberated 115 ppm NO. Mice were exposed in an inhalation chamber to 115 ppm NO, 900 ppm isobutyl nitrite, or 900 ppm cyclohexyl nitrite for 45 min/day. Following a single exposure, NO did not affect peripheral blood cell counts, while isobutyl and cyclohexyl nitrites reduced cell numbers. After 14 daily exposures, isobutyl nitrite, but not cyclohexyl nitrite or NO, reduced peritoneal macrophage tumoricidal activity. The nitrite esters likely caused immunotoxicity by mechanisms other than NO release.

Animals↗