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Biomedical subjects

M O Smith

Publications and source records attributed to M O Smith.

At least 19 recordsLinked to original sources
PubMed1992

Research note: broiler acclimation to heat distress and feed intake effects on body temperature in birds exposed to thermoneutral and high ambient temperatures.

Relationships between ambient temperature, bird acclimation to cycling temperature, heat distress, and feed consumption were evaluated in two experiments. In the first experiment, birds previously acclimated to cycling temperature heat distress (24 to 35 C) for two 24-h cycles were observed to have 24% lower (P less than .01) feed consumption than birds previously housed at 24 C and experiencing their first heat distress exposure. A significant (P less than .01) acclimation history by ambient temperature interaction was detected, with acclimated birds having a higher rectal temperature (42.3 versus 41.2 C) when housed at 24 C and a lower rectal temperature (44.2 versus 44.6 C) when exposed to 35 C than did the unacclimated controls. In the second experiment, feed intake and acclimation effects were separated by precision-feeding birds 0, 5, and 10% of body weight. Rectal temperature in the 24 C and 35 C environments increased linearly (P less than .01) as feeding level increased for both acclimated and unacclimated birds. Similar to the first experiment, an ambient temperature by acclimation history interaction was detected (P less than .01), with acclimated birds exhibiting increased body temperature when housed in thermoneutral environments and lower body temperature when exposed to high ambient temperature distress.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1992

Elevated vascular cell adhesion molecule-1 in AIDS encephalitis induced by simian immunodeficiency virus.

AIDS encephalitis is a common sequela to HIV-1 infection in humans and simian immunodeficiency virus (SIVmac) infection in macaques. Although lentiviral-infected macrophages comprise parenchymal inflammatory infiltrates in affected brain tissue, the mechanisms responsible for leukocyte trafficking to the central nervous system in AIDS are unknown. In this study, we investigated the expression of various endothelial-derived leukocyte adhesion proteins in SIVmac-induced AIDS encephalitis. Encephalitic brains from SIVmac-infected macaques, but not uninflamed brains from other SIVmac-infected animals, were found to express abundant vascular cell adhesion molecule-1 (VCAM-1) protein on the majority of arteriolar, venular, and capillary endothelial cells. Soluble VCAM-1 concentrations in cerebrospinal fluid (CSF) from encephalitic animals were increased approximately 20-fold above those from animals without AIDS encephalitis. Expression of other endothelial-related adhesion molecules, including E-selectin, P-selectin, and intercellular adhesion molecule-1 (ICAM-1), was not uniformly associated with AIDS encephalitis. Thus, the presence of VCAM-1 in both brain and CSF was uniformly associated with SIVmac-induced disease of the central nervous system, and this expression may, at least in part, influence monocyte and lymphocyte recruitment to the central nervous system during the development of AIDS encephalitis. Moreover, measurement of soluble VCAM-1 in CSF may assist in the clinical assessment of animals or people with AIDS.

AIDS Dementia Complex↗
PubMed1991

Localization of simian immunodeficiency virus in the central nervous system of rhesus monkeys.

Simian immunodeficiency virus (SIV), like the human immunodeficiency virus (HIV), is a lentivirus that is both immunosuppressive and neurovirulent. Rhesus macaques (Macaca mulatta) inoculated with SIV often develop a giant cell encephalitis similar to that seen in humans infected with HIV. The authors examined SIV expression by immunohistochemistry and RNA in situ hybridization in the cerebrum, cerebellum, choroid plexus, and spinal cord from five macaques with and two macaques without giant cell encephalitis. Selected portions of the central nervous system (CNS) also were examined by electron microscopy. Simian immunodeficiency virus was detected in the CNS of all seven monkeys whether or not they had giant cell encephalitis. Both SIV antigen and RNA were present in all levels of the CNS examined. Macrophage/giant cell lesions always contained viral RNA and antigen and were the only sites where viral particles were detected by electron microscopy. However, SIV antigen and RNA also were commonly associated with small vessels, the choroid plexus, and meninges; these were the only locations where virus was detected in animals without giant cell encephalitis. Immunophenotyping showed that the cellular infiltrates consisted primarily of monocyte/macrophages and occasional CD8-positive T cells. Macrophages and T cells also were present in the stroma of the choroid plexus and were intimately associated with vessels in the CNS of SIV-infected but not uninfected macaques. Simian immunodeficiency virus infection of the macaque CNS provides an excellent model for studying the pathogenesis, treatment, and prevention of HIV-1-encephalitis.

Animals↗
PubMed1990

Type C retroviral expression in spontaneous feline olfactory neuroblastomas.

Three cases of spontaneous olfactory neuroblastoma (ONB) in domestic cats were morphologically and immunocytochemically characterized. Diagnostic light microscopic features included Flexner and Homer-Wright rosettes, while ultrastructurally the cells had neuritic processes, intracellular intermediate filaments, and intercellular junctions. Immunocytochemically, the tumors stained positively for neuron-specific enolase, cytokeratins, and S-100 protein antigens. In each case, a key finding was the identification of numerous mature type C retroviral particles within the tumors. In one case, budding of viral particles from the plasmalemma of tumor cells suggested the source of mature particles. This cat and one other were tested, and both were serologically positive for feline leukemia virus (FeLV). The virus in the tumors was identified as FeLV by polymerase chain reaction and immunocytochemistry. No other neoplasms were found in any of the cats, nor was there similar evidence of active viral infection in other non-tumor tissues, including the brain. Although the relationship between FeLV infection and ONB is uncertain, our findings indicate that FeLV should be investigated as an etiologic agent of ONB.

Animals↗
PubMed1989

Neurologic abnormalities as the predominant signs of neoplasia of the nasal cavity in dogs and cats: seven cases (1973-1986).

Neurologic abnormalities were the predominant historic and physical findings in 5 dogs and 2 cats with primary nasal cavity tumors that had invaded the cranial vault. Seizures, behavior changes, and obtundation were the most common signs. Other neurologic signs included paresis, ataxia, circling, visual deficit, and proprioceptive deficit. Although 1 dog and 2 cats had historic findings of mild respiratory disease, no physical abnormalities related to the respiratory tract were found in any of the 7 animals. Nasal cavity neoplasia was suggested by radiographic and computed tomographic studies and was confirmed histopathologically in each case. The nasal tumor types in the 5 dogs were epidermoid carcinoma (n = 1), adenocarcinoma (n = 2), solid carcinoma (n = 1), and anaplastic chondrosarcoma (n = 1). An esthesioneuroblastoma was found in each cat. Radiation therapy was effective for 3 months in palliating the clinical signs in the 2 dogs in which it was used. Neoplasia of the nasal cavity should be considered in the differential diagnosis for animals with neurologic signs suggestive of cerebral disorders.

Adenocarcinoma↗
PubMed1989

MPTP-induced Parkinson-like disease in sheep: clinical and pathologic findings.

Eight ewes, divided into two groups based on age, with group 1 7-8 and group 2 1-3 years old, respectively, were administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intravenously (IV) at cumulative doses of 2.0 to 34.6 mg/kg body weight. Two group 1 sheep, given cumulative doses of 2 and 8.5 mg/kg, developed persistent severe neurologic signs of body stiffness and rigidity, paucity of movement, intention body tremors, and abnormal body posture and stance similar to those signs in MPTP-induced disease in people and primates. After their acute onset, these persistent signs were nonprogressive up to the observation period of 32 days post infusion. None of the younger ewes had persistent neurologic symptoms at equivalent cumulative doses (9.0 mg/kg). The only pathologic changes were microscopic lesions in the central nervous system, consisting of bilaterally symmetrical neuronal chromatolysis and necrosis limited to the substantia nigra and locus ceruleus. These lesions were found in two persistently affected and two younger sheep, suggesting age-based differences in dose response and the threshold of clinical expression of disease. Serum MPTP half-life was 11 days. Thus sheep exposed to MPTP could be an alternative model to the primate for the comparative study of clinical, pathologic, and biochemical mechanisms in MPTP neurotoxicity and Parkinson's disease in people.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

An acupuncture programme for the treatment of drug-addicted persons.

Over the past 13 years, Lincoln Hospital, New York City, has used acupuncture as the primary method of treatment for drug-addicted persons. The programme receives, on a daily out-patient basis, 200 drug-addicted persons for detoxification. Acupuncture relieves withdrawal symptoms, prevents the craving for drugs and increases the rate of participation of patients in long-term treatment programmes. The best results have been obtained by treating patients in an open-group setting, using acupuncture points in the external ear with needles without electrical stimulation. The same points are used at each visit, regardless of the type of drug to which the person is addicted. This method is also used for the treatment of persons suffering from stress. The National Acupuncture Detoxification Association (NADA) has conducted successful training programmes for physicians and related staff in using the technique and philosophy of traditional Chinese acupuncture. These training programmes usually include courses in counseling skills, ethical responsibilities and sterilization procedures that are appropriate to local conditions. NADA has begun to operate a pilot programme to treat approximately 1,000 drug abusers and people who are under a high level of stress, which may lead them to the abuse of drugs. It is assumed that acupuncture, in conjunction with other drug-demand reduction programmes, can make a significant impact on the illicit demand for drugs by reaching this entire range of patients.

Acupuncture Therapy↗
PubMed1987

Potassium balance of the 5 to 8-week-old broiler exposed to constant heat or cycling high temperature stress and the effects of supplemental potassium chloride on body weight gain and feed efficiency.

Four experiments were conducted to study the impact of ambient temperature and relative humidity stress upon K excretion and the effects of KCl supplementation of broilers exposed to chronic heat and cycling temperature stress. Potassium excretion, corrected for K intake and body weight, increased by 633% as ambient temperature was elevated from a constant 24 C to a constant 35 C. Feed (.73% K) and drinking water (0% K) were supplemented with KCl so effects of KCl on live weight gain and feed efficiency could be evaluated. In a previous study at thermoneutral temperature, no benefit of supplemental KCl was observed whereas in this study a dietary level of 1.5 to 2% K in the form of KCl improved gain under conditions of chronic high ambient temperature stress. This equals about 1.8 to 2.3 g K per chick daily or about .24 to .3% of the drinking water.

Animals↗
PubMed1986

Detoxification of high tannin sorghum grains.

One in vitro and two in vivo experiments were conducted to determine appropriate methodology for and effects of detoxifying Darset, Redlan, and one commercial hybrid brown sorghum grain variety in threonine-deficient and nutritionally complete poultry rations. The detoxification procedure, which involves adding water to sorghum grain to bring dry matter to 70% and subsequent anaerobic incubation at 32 C, removes up to 100% of the chemically detectable tannin. Rate of tannin elimination was dependent upon sorghum grain variety with commercial brown sorghum requiring approximately 3 days longer than the Darset for tannin elimination. Detoxification of high tannin sorghum grains improved (P less than .05) growth rate and feed efficiency dramatically in threonine-deficient, crystalline amino acid-fortified rations; the same process applied to low tannin sorghum grains was without benefit. The desirable effects of this type of grain processing appear to be due to the reduced grain tannin content. Including detoxified sorghum grains in a practical-type broiler ration failed to elicit a weight gain response although feed efficiency was improved by 13% over untreated sorghum and 3% over corn grain. Lack of a gain response was likely due to the excess protein included in the basal diet. This type of grain processing offers an alternative method of reducing sorghum grain tannin content and is likely of greatest value in rations containing marginal indispensable amino acid and protein levels.

Amino Acids↗
PubMed1986

High chronic ambient temperature stress effects on broiler acid-base balance and their response to supplemental ammonium chloride, potassium chloride, and potassium carbonate.

Four experiments were conducted to evaluate the effect of heat stress on acid-base status and the birds' response to supplemental KCl and KCO3. The corn-soybean meal fish-meal basal ration (.73% K+) contained more K+ and Cl- than is recommended by the National Academy of Sciences for chicks reared under near optimal conditions (24 C and 55% relative humidity). Chicks reared under continuous thermostress (35 C, 70% relative humidity) exhibited panting phase blood alkalosis (pH of 7.46). Supplementing drinking water with .2% NH4Cl reduced panting phase blood pH to normal values and increased live weight gain (23%) and feed efficiency (7.7%). Supplementing drinking water with .15% KCl also increased (P less than .05) live weight gain (46%) and feed efficiency (15.4%) but did not affect (P less than .46) blood pH. A significant (P less than .01) interaction existed between NH4Cl and KCl for body weight gain. Adding .2% NH4Cl to broiler drinking water reduced the level of KCl required in drinking water to optimize weight gain to .1% KCl. Potassium chloride alone, or with NH4Cl, can alleviate some consequences of heat stress, but supplementing drinking water with a high level of NH4Cl (.5%) decreased (P less than .05) blood pH to acidotic levels and reduced body weight gain. Potassium chloride supplementation exacerbated NH4Cl toxicity. Potassium carbonate reduced (P less than .05) body weight gain indicating that the response may not be attributed to K+ alone. Beneficial effects of NH4Cl therapy for heat stressed broilers are speculative.

Acid-Base Equilibrium↗
PubMed1985

Chronic heat stress and respiratory alkalosis: occurrence and treatment in broiler chicks.

The occurrence of respiratory alkalosis and potential benefit derived from treatment were examined in thermostressed 4-week-old broiler chicks. Blood pH was greater (P less than .05) in heat-stressed (32 C) panting birds (7.395) than either nonpanting (7.28) or birds raised at 24 C (7.28). Acute thermostress, obtained by elevating ambient temperature from 32 to 41 C over a 20-min period further elevated (P less than .05) blood pH to 7.521. Chronic heat-stressed broiler chicks suffer from intermittent respiratory alkalosis during panting; with acute heat stress, chicks pant continuously and suffer from alkalosis. Including .5% sodium bicarbonate (NaHCO3) in the diet of birds subjected to chronic heat stress enhanced body weight gain by 9% even though it tended (P less than .10) to increase blood pH in nonpanting birds. Adding .3 or 1% ammonium chloride (NH4Cl) to diets decreased blood pH (P less than .01) to 7.194 and increased (P less than .05) body weight gains by 9.5 and 25%, respectively. Effects appeared linear with NH4Cl dose to 1% NH4Cl, but 3% NH4Cl elevated weight gains by only 8% and precipitated blood acidosis (pH 7.09) in nonpanting birds. Supplementing the 1% NH4Cl diet with .5% NaHCO3 increased weight gains an additional 9%. Manipulating sodium: chloride ratios by addition of calcium chloride increased body weight gain 8% and slightly reduced severity of alkalosis. Data indicate that blood alkalosis limits growth rate of broiler chicks reared under chronic thermostress and that the respiratory alkalosis and weight gain depressions attributed to thermostress can be partially alleviated dietarily.

Alkalosis, Respiratory↗
PubMed1985

Feed intake effects upon gain, carcass yield, and ration digestibility in broilers force fed five feed intakes.

Broiler chicks were force fed 75, 100, 125, 140 and 160% of the consumption observed by ad libitum-fed controls to examine feed intake effects upon productivity. Live body weight gain increased with feed intake up to the 140% consumption but was depressed above this point. Feed efficiency and fat, ash, ration (corrected for uric excretion mass), protein (corrected for uric acid excretion nitrogen), and starch digestibility estimates declined by 30, 56, 25, 16, 16, and 2%, respectively, as feed consumption increased from 75 to 160% of ad libitum consumption. Neutral detergent fiber digestibility was not affected by amount of feed consumption. Initial digesta passage rate, estimated by first appearance of ferric oxide in feces, averaged 215 min and was not correlated (P greater than .4) with feed intake. Gastrointestinal tract mass plus contents increased with feed intake and accounted for up to 67% of the increased live body weight gain. Birds apparently adjusted to feed intake level by varying gastrointestinal tract size (mass) and not passage rate. Dressing percentage declined from a high of 73% for birds fed at the lowest feed intake to a low of 63% at the highest feed intake. Carcass gain was 50% greater for the 160 vs 75% group, but most of this (41%) was reached at the ad libitum consumption level. Carcass gain-to-feed ratios were .42, .41, .32, .27, and .21 for the five intakes, respectively. Drumstick, breast, and thigh gains were not (P greater than .01) influenced by increased feed consumption above the ad libitum-fed controls but were depressed (P greater than .05) at the 75% feed intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Comparison of ferric oxide and ytterbium chloride as digesta markers in broiler chicks.

The capacity of Fe2O3 to mimic initial and 5-hr postdose digesta flow rate was evaluated by comparison with Yb-labeled soybean meal in 5-week-old chicks. First visually apparent Fe2O3 corresponded identically with first chemically detectable Fe and Yb. Five-hr marker excretions as a percent of that originally dosed were similar (P greater than .4) for the two markers. Data indicate that first visual appearance of Fe2O3 is sufficient to estimate initial digesta passage rate and that Fe2O3 and Yb-labeled soybean meal have similar flow rates. Because Yb-labeled soybean meal flows with the digesta particulate phase, data also indicate that either Fe2O3 flows with the particulate phase or that broiler digesta liquid and particulate passage rates are similar.

Animals↗
PubMed1985

Exogenous growth hormone levels predict attentional performance: a preliminary report.

The imminent commercial availability of synthetic growth hormone (GH) and the potential for large scale and possibly indiscriminant use mandate a critical examination of possible adverse effects. This double-blind study examined the effects of human GH on attention. Treatment of eight GH-deficient children, aged 8.7 to 14.1 years, was suspended to establish base lines. Injections with GH (0.1 units/kg) and placebo followed in counterbalanced 2-week periods. At the end of each period, GH levels were assayed, and attention was tested. Scores earned under the GH condition did not differ from base line and placebo values. However, patients displaying high levels (14 +/- 2.12 ng/ml) of exogenous GH 12 hours after injection generally surpassed norms and patients with low levels (3.5 +/- 1.12 ng/ml) of GH under all conditions of the experiment. If 12-hour levels in this study are indicative of the fate of GH received during therapy, prolonged use of GH may bring benefits to attention that vary directly with half-life.

Adolescent↗
PubMed1977

Cerebral lateralization of haptic perception: interaction of responses to Braille and music reveals a functional basis.

Normally, haptic perception of the left hand surpasses that of the right. But simultaneously playing music into the left (but not the right) ear reverses this superiority. This suggests that the left cerebral hemisphere has full haptic perceptual capability, which is subject to right hemisphere interference unless the latter's attentional mechanisms are engaged by contralateral peripheral stimulation.

Adult↗