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Biomedical subjects

J M Davis

Publications and source records attributed to J M Davis.

At least 109 records · Page 6Linked to original sources
PubMed1998

Exercise effects on IFN-beta expression and viral replication in lung macrophages after HSV-1 infection.

Mice exercised to fatigue and exposed to herpes simplex virus type 1 (HSV-1) exhibit greater mortality than control mice. In this study, we examined lung macrophage resistance to HSV-1 after exercise in terms of both viral replication and interferon (IFN)-beta production. We utilized the reverse transcriptase-rapid polymerase chain reaction to measure the IFN-beta mRNA content in alveolar macrophages. IFN release was measured with a bioassay, and viral replication within the macrophage was assessed by plaque titration. Exercised (Ex) mice ran on a treadmill until fatigue while control (Con) mice remained in lanes above the treadmill. After exercise, alveolar macrophages were removed and incubated with HSV-1. Alveolar macrophage IFN-beta mRNA was greater in Ex than in Con mice. Culture supernatant from infected macrophages showed a higher degree of IFN release and a higher number of infectious viral particles in Ex vs. Con mice. It is likely that the increase in IFN-beta mRNA occurs in response to a higher degree of viral replication. These results suggest that macrophages from Ex mice are less resistant to infection with HSV-1.

Animals↗
PubMed1998

Exercise effects on lung tumor metastases and in vitro alveolar macrophage antitumor cytotoxicity.

This study examined the effects of moderate and prolonged exercise on 1) lung tumor metastases and 2) alveolar macrophage antitumor response in vitro. C57B1/6 mice were assigned to either Ex-30 (30-min run), Ex-F (run to fatigue), Ex-F-24 h (run to fatigue 24 h before tumor injection), or Con (rested in lanes above the treadmill). Mice received intravenous injections of syngeneic B16 melanoma cells 30 min postexercise. Lungs were removed 7 or 10 days later, and tumor foci were counted. Ex-F had fewer tumors than either Ex-30 or Con, whereas Ex-F-24 h also showed a strong trend toward fewer tumors. The initial localization of tumor cells in the lungs after injection was not different among groups. For the in vitro experiment, mice were killed immediately after exercise or 8 h later. Alveolar macrophages were removed and cultured in vitro with B16 melanoma cells. The growth of the tumors cultured with macrophages from Ex-F was lower than Con after exercise and, to a lesser extent, 8 h later. In Ex-30, this effect was only found immediately after exercise. The data suggest that prolonged exercise has a protective effect on lung tumor metastases and enhances alveolar macrophage antitumor cytotoxicity.

Animals↗
PubMed1998

Effects of mode and carbohydrate on the granulocyte and monocyte response to intensive, prolonged exercise.

The influence of exercise mode and 6% carbohydrate (C) vs. placebo (P) beverage ingestion on granulocyte and monocyte phagocytosis and oxidative burst activity (GMPOB) after prolonged and intensive exertion was measured in 10 triathletes. The triathletes acted as their own controls and ran or cycled for 2.5 h at approximately 75% maximal O2 uptake, ingesting C or P (4 total sessions, random order, with beverages administered in double-blind fashion). During the 2. 5-h exercise bouts, C or P (4 ml/kg) was ingested every 15 min. Five blood samples were collected (15 min before exercise, immediately after exercise, and 1.5, 3, and 6 h after exercise). The pattern of change over time for GMPOB was significantly different between C and P conditions (P </= 0.05), with postexercise values lower during the C trials. Little difference was measured between running and cycling modes. C relative to P ingestion (but not exercise mode) was associated with higher plasma levels of glucose and insulin, lower plasma levels of cortisol and growth hormone, and lower blood neutrophil and monocyte cell counts. These data indicate that C vs. P ingestion is associated with higher plasma glucose levels, an attenuated cortisol response, and lower GMPOB.

Adult↗
PubMed1998

Verapamil for the treatment of acute mania: a double-blind, placebo-controlled trial.

OBJECTIVE: This study investigated the efficacy of verapamil in acute mania. METHOD: The study was a 3-week double-blind, random-assignment, parallel-group, placebo-controlled inpatient trial of verapamil for patients with acute mania. Of the 32 study patients, 15 were given placebo and 17 were given verapamil. RESULTS: Mean absolute change scores on the Mania Rating Scale at endpoint, with baseline scores as the covariates, did not differ between the verapamil and placebo groups. There were no significant differences between the two groups in age, sex, and presence of psychosis. CONCLUSIONS: The investigators found no benefit of verapamil over placebo in treating acute mania.

Acute Disease↗
PubMed1998

Methylcyclopentadienyl manganese tricarbonyl: health risk uncertainties and research directions.

With the way cleared for increased use of the fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) in the United States, the issue of possible public health impacts associated with this additive has gained greater attention. In assessing potential health risks of particulate Mn emitted from the combustion of MMT in gasoline, the U.S. Environmental Protection Agency not only considered the qualitative types of toxic effects associated with inhaled Mn, but conducted extensive exposure-response analyses using various statistical approaches and also estimated population exposure distributions of particulate Mn based on data from an exposure study conducted in California when MMT was used in leaded gasoline. Because of limitations in available data and the need to make several assumptions and extrapolations, the resulting risk characterization had inherent uncertainties that made it impossible to estimate health risks in a definitive or quantitative manner. To support an improved health risk characterization, further investigation is needed in the areas of health effects, emission characterization, and exposure analysis.

Administration, Inhalation↗
PubMed1998

Biological effects of low-level exposures: a perspective from U.S. EPA scientists.

Biological effects of low-level exposures (BELLE) may be very important in characterizing the potential health risks of environmental pollutants. Before some features of BELLE, such as effects that may be modulated by adaptive or defense mechanisms, can be taken into greater consideration in U.S. Environmental Protection Agency risk assessments, however adequate information on a toxicant's mode of action and answers to other questions are needed.

Adaptation, Physiological↗
PubMed1998

Imidazenil, a positive allosteric GABAA receptor modulator, inhibits the effects of cocaine on locomotor activity and extracellular dopamine in the nucleus accumbens shell without tolerance liability.

Imidazenil, a benzodiazepine recognition site ligand that acts as partial positive allosteric modulator of gamma-aminobutyric acid (GABA) action at GABAA receptors, inhibits in a dose-dependent manner (0.56-2.5 micromol/kg i.p. to rats) the cocaine-induced increase in dopamine (DA) content in the dialysates of the nucleus accumbens shell and striatum and also inhibits cocaine-induced locomotor activity. Diazepam, a full allosteric modulator of GABA action at GABAA receptors, in a dose of 4.4 micromol/kg i.p. also attenuates the cocaine-induced increase in DA content in the dialysates of nucleus accumbens shell, and striatum and the cocaine-induced locomotor activity. However, imidazenil (2.5 micromol/kg i.p.) fails to reduce spontaneous locomotor activity, whereas diazepam (4.4 micromol/kg i.p.) elicits sedation and ataxia and clearly impairs spontaneous locomotor activity. When added in vitro, both imidazenil and diazepam potentiate the GABA-mediated reduction of the ventral tegmental area DA neuron firing rate. After protracted treatment (14 days/three times a day with an increasing-dose schedule), the inhibitory actions of imidazenil fail to develop tolerance, whereas the actions of diazepam exhibit high tolerance liability. We conclude that imidazenil is devoid of tolerance liability and that, via a GABAA-mediated reduction in the extracellular DA in nucleus accumbens shell, it might reduce the psychomotor activity and reinforcing properties of cocaine.

Allosteric Regulation↗
PubMed1997

The Altman Self-Rating Mania Scale.

We report on the development, reliability, and validity of the Altman Self-Rating Mania Scale (ASRM). The ASRM was completed during medication washout and after treatment by 22 schizophrenic, 13 schizoaffective, 36 depressed, and 34 manic patients. The Clinician-Administered Rating Scale for Mania (CARS-M) and Mania Rating Scale (MRS) were completed at the same time to measure concurrent validity. Test-retest reliability was assessed separately on 20 depressed and 10 manic patients who completed the ASRM twice during washout. Principal components analysis of ASRM items revealed three factors: mania, psychotic symptoms, and irritability. Baseline mania subscale scores were significantly higher for manic patients compared to all other diagnostic groups. Manic patients had significantly decreased posttreatment scores for all three subscales. ASRM mania subscale scores were significantly correlated with MRS total scores (r = .718) and CARS-M mania subscale scores (r = .766). Test-retest reliability for the ASRM was significant for all three subscales. Significant differences in severity levels were found for some symptoms between patient ratings on the ASRM and clinician ratings on the CARS-M. Mania subscale scores of greater than 5 on the ASRM resulted in values of 85.5% for sensitivity and 87.3% for specificity. Advantages of the ASRM over other self-rating mania scales are discussed.

Adult↗
PubMed1997

Depression during mania. Treatment response to lithium or divalproex.

BACKGROUND: Little information exists from controlled studies about clinical characteristics that predict treatment response in mania. The presence of depressive symptoms during manic episodes may be associated with poor response to psychopharmacological treatments. This is an investigation of the relation between depressive symptoms and treatment response in acute manic episodes. METHODS AND DESIGN: In a parallel-group, double-blind study, 179 patients hospitalized for acute manic episodes were randomized to receive divalproex sodium, lithium carbonate, or placebo (ratio, 2:1:2). The study was carried out at 9 academic medical centers. Patients had comprehensive evaluations of behavior and symptoms before and during 3 weeks of treatment. The primary outcome measure, change in mania factor scores derived from the Schedule for Affective Disorders and Schizophrenia: Change Version, was compared in patients with and without depressive symptoms at baseline according to nurse- or physician-rated scales. RESULTS: Depressive symptoms were associated with poor antimanic response to lithium and with better response to divalproex. This was not due to differences in overall severity of illness, substance abuse, gender, age, or history. CONCLUSIONS: These data suggest that even a modest level of pretreatment depression-related symptoms is a robust predictor of lithium nonresponse, and is associated with better response to divalproex. Although their overall efficacy in acute mania is similar, lithium and divalproex may be most effective in clinically and biologically distinct groups of patients.

Adult↗
PubMed1997

Portal vein gas, a changing clinical entity. Report of 7 patients and review of the literature.

OBJECTIVE: To assess the clinical significance of portal vein gas (PVG) demonstrated by computed tomography (CT). DESIGN: Review of medical records. SETTING: Three network-affiliated hospitals providing both primary community-based and tertiary services. METHODS: Review of diagnosis, clinical circumstances, and significance of PVG in 7 patients detected by CT during a 3-year period in 3 affiliated hospitals. RESULTS: Four of 7 patients underwent laparotomy; 1 patient refused surgery. Two patients were treated with intravenous antibiotics only and had uneventful clinical courses. Of the 3 patients who died, 1 refused and 2 underwent laparotomy. CONCLUSIONS: This series indicates that more sensitive imaging and more widespread use of endoscopic retrograde cholangiopancreatography, colonoscopy, and liver transplantation have changed the clinical presentation of PVG; PVG may be found in various clinical settings that do not mandate laparotomy; and the significance of PVG must be derived from the clinical context of the individual patient.

Adult↗
PubMed1997

A vegetative storage protein homolog is expressed in the growing shoot apex of hybrid poplar.

The ability of poplars (Populus deltoides Bartr. ex Marsh., and Populus trichocarpa Torr. and Gray) to sequester nitrogen in stems in preparation for winter has been associated with the massive accumulation of protein bodies in the bark and xylem ray parenchyma. These protein bodies contain a bark storage protein (BSP) that can account for up to 30% of the total soluble bark protein during the winter months. Perhaps the plant's ability to efficiently cycle nitrogen through BSP is an important aspect of its growth potential. Sequence analysis of BSP led to the identification of a leaf-associated homolog, win4, which was initially isolated because its transcript increased in abundance upon mechanical wounding. The goal of this work was to characterize this putative leaf-associated vegetative storage protein, and determine whether it might perform a storage role in vivo. Antibodies, produced against protein synthesized upon over-expression of the win4 coding region in Escherichia coli, were used to examine the relative abundance of WIN4 protein in response to supplemental nitrogen, and during development. The transcript and protein were most abundant in the youngest leaves and also increased with nitrogen fertilization. Immunolocalization of the protein was performed and showed that WIN4 was associated with cells surrounding the vasculature, and cells of the lower epidermis and stipules of immature leaves. Under moderate nitrogen fertilization regimes, WIN4 accounted for only about 2% of total soluble leaf protein; however, given the cellular specificity and enhancement with nitrogen, the protein is regulated in a manner similar to other vegetative storage proteins. Since poplar is amenable to DNA transformation and regeneration, it is now possible to ask direct questions about the role these proteins play in nitrogen storage in rapidly expanding or in dormant tissue. This type of analysis could determine whether these proteins mainly ameliorate the toxic effects of excess nitrogen, if they are instrumental in controlling nitrogen allocation or if they simply represent an efficient method for sequestering this valuable nutrient.

Cloning, Molecular↗
PubMed1997

Staphylococcal protein A binding to canine IgG and IgM.

Staphylococcal protein A (SpA) binds with high affinity to immunoglobulins from many species, making it a useful reagent for immunoassays and immunoglobulin purification procedures. However, its use is limited by poor reactivity with some immunoglobulin subclasses including human IgG3 and murine IgG1. Reports of SpA's reactivity with canine immunoglobulins have been inconsistent. Because the most recent reports indicated a much greater reactivity of purified SpA with canine immunoglobulins than was suggested by our observations, we quantitatively reevaluated the binding of canine IgG and IgM to Cowan I strain SpA under the conditions of use in our laboratory. IgG and IgM were purified from pooled normal canine plasma by affinity chromatography with heavy chain specific polyclonal anti-IgG and anti-IgM antibodies. The purified IgG and IgM were assessed for SpA reactivity by affinity chromatography using a SpA-agarose column. The relative proportions of total chromatographed IgG or IgM in the flow-through (SpA-nonbindable) and eluate (SpA-bindable) fractions were determined by absorbance at 280 nm. The IgG and IgM in each immunoglobulin fraction were also nonspecifically adsorbed to microtitration plates and tested for reactivity with 125I-SpA using a solid phase immunoradiometric assay (IRMA). Approximately 18% of the affinity purified canine IgG and 33% of the affinity purified canine IgM did not bind to the SpA affinity column and were also unreactive with 125I-SpA using the IRMA. A second approach using a different polyclonal antibody to canine IgG yielded similar results: about 21% of the purified IgG was unreactive with SpA. Incomplete reactivity of SpA with canine IgG and IgM limits the usefulness of SpA in canine immunologic procedures.

Animals↗
PubMed1997

Effect of immediate fluid resuscitation on the rate, volume, and duration of pulmonary vascular hemorrhage in a sheep model of penetrating thoracic trauma.

STUDY OBJECTIVE: To determine the effects of early fluid resuscitation on the rate, volume, and duration of hemorrhage using a sheep model of uncontrolled pulmonary vascular hemorrhage. METHODS: Sixteen adult sheep were anesthetized and fitted with catheters to measure systemic and pulmonary artery pressures. A branch of the pulmonary vein was then lacerated through an anterolateral thoracotomy, and a chest tube was inserted to monitor hemorrhage volume. Eight animals were assigned to the immediate fluid (IF) resuscitation group and were given 30 mL/kg of lactated Ringer's solution over a period of 10 minutes; this treatment was repeated once if normotension was not achieved. The other eight animals received no fluid (NF) and served as nonresuscitated controls. RESULTS: The IF animals had a mean hemorrhage volume of 3,494 +/- 1,525 mL, compared with 1,594 +/- 689 mL in the NF group (P < .001). Hemorrhage stopped spontaneously in the NF group at a mean of 29 +/- 9 minutes but took 48 +/- 11 minutes in the IF group (P = .003). During the 20-minute period of fluid resuscitation, the IF animals bled at twice the rate of the NF animals (90 +/- 33 versus 46 +/- 22 mL/minute, respectively; P = .02). During the 10-minute interval after fluids were administered, the rate of hemorrhage remained brisk at 73 +/- 57 mL/minute in the IF group but virtually stopped in the NF group (6 +/- 7 mL/minute; P = .02). CONCLUSION: In this sheep model of uncontrolled pulmonary vascular hemorrhage, immediate fluid resuscitation significantly increased the rate, volume, and duration of hemorrhage. The vigorous administration of fluids to patients with penetrating chest trauma has the potential to significantly increase blood loss.

Animals↗
PubMed1997

Molecular cloning, structure and expression of an elicitor-inducible chitinase gene from pine trees.

We have cloned, sequenced, and examined the expression of genes from pine trees that appear to encode extracellular class II chitinase. Nucleotide sequence analysis indicates a coding sequence composed of three exons interrupted by two introns at locations identical to those found in other chitinase genes that possess introns. One of the genes, Pschi4, potentially encodes a protein that shares 62% amino acid sequence identity through the catalytic domain with class II chitinase from tobacco. In contrast, Pschi1 contains a stop codon in the first exon and may be a pseudogene. Pschi4 genes are conserved in several species of pine, and appear to comprise a small multigene family. Treatment of pine cell suspension cultures with the general elicitor chitosan induced Pschi4 expression. The regulatory sequences associated with the Pschi4 gene were sufficient to direct chitosan-inducible expression of Pschi4 in transgenic tobacco plants, which indicates that Pschi4 is an actively expressed member of the multigene family. The observation that the Pschi4 gene from pine (a gymnosperm) was appropriately regulated by chitosan in tobacco (an angiosperm) suggests that the signaling pathways that mediate chitosan-induced transcription are highly conserved in the plant kingdom.

Amino Acid Sequence↗
PubMed1997

Cytokine and nitric oxide production in the acute phase of bacterial cell wall-induced arthritis.

We have investigated the temporal relationship among proinflammatory cytokine expression, nitric oxide (NO) production and joint inflammation in the acute phase of bacterial cell wall-derived peptidoglycan polysaccharide (PG/PS)-induced arthritis. Acute joint inflammation was induced in female LEW/N rats by a single intraperitoneal injection of PG/PS. Arthritis index and paw volume were quantified and joint histopathology was evaluated during acute joint inflammation (0-10 days). Tumor necrosis factor (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6) were determined by bioassay whereas nitric oxide (NO) was quantified by measuring serum nitrate/nitrite levels via the Griess procedure. We found that serum levels of TNF and serum IL-1 preceded the increase in IL-6 and NO production. Furthermore, the production of these proinflammatory cytokines and NO preceded bone erosion and osteoclast activity. Erosion of subchondral bone preceded pannus formation and cellular synovitis in the acute phase of PG/PS-induced arthritis. The temporal expression of TNF, IL-1, IL-6 and NO suggest a cascade of inflammatory mediators in which monocytes and macrophages respond to PG/PS with enhanced synthesis of TNF and IL-1, which may in turn promote the synthesis of IL-6 and NO. We postulate that one or more of these inflammatory events are responsible for initiating the subchondral bone erosion observed in acute joint inflammation.

Acute Disease↗
PubMed1997

Sexual arousal to erotic and aggressive stimuli in sexually coercive and noncoercive men.

Sexual arousal to erotic stimuli depicting various levels of force were examined among college men. Study 1 used phallometric indices to measure penile circumferential change during combined audio-tape and slide presentations varying in degree of force. The results indicated that the sexually coercive group exhibited more penile tumescence than controls to scenes involving verbal pressure and verbal threats. Analyses across time blocks suggested that control participants inhibited sexual arousal with the introduction of force cues but that the sexually coercive group did not. Study 2 was a replication of Study 1 without slides. Both groups showed increases in penile tumescence in response to the consent scenario. Only the sexually coercive men demonstrated significant tumescence in response to force scenarios. The results indicated that the sexually coercive males had a lower threshold for arousal to sexual cues and did not inhibit sexual arousal when force cues were introduced.

Adolescent↗
PubMed1997

Effects of exercise intensity on natural killer cell activity in women.

Exercise effects on natural killer cell (NK) activity in men appear to be intensity dependent, but there is very little data in women. We tested the effect of high versus moderate-intensity exercise relative to non-exercising controls on NK cytolytic activity (NK activity) in women using oral contraceptives. Subjects (n = 8) participated in 3 treatments consisting of 25 min of cycle ergometer exercise at 80% (HI-INT) and 40% (MOD-INT) VO2max, and a 25 min control (CON) session in which the subject remained seated on the cycle ergometer, but did not exercise. Blood was obtained prior to exercise, immediately after, and at 90 min and 3 h after exercise. During CON, NK activity gradually increased and cortisol gradually decreased during the approximately 3.5 h experimental period. Relative to CON, HI-INT increased NK activity, %CD56+ (NK) cells, and plasma norepinephrine immediately post exercise (p < or = 0.05). There was also a trend for decreased NK activity at 90 min (p = 0.075). No differences among treatment groups were found by 3 h post exercise. In MOD-INT, there were no differences from CON in any variable at any time. These data suggest that the typical NK response to intensive exercise in men, which consists of a brief increase followed by a more prolonged suppression, also occurs in women using oral contraceptives. However, it is important to use time-matched control measurements in determining this response.

Adult↗