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Biomedical subjects

J G Phillips

Publications and source records attributed to J G Phillips.

At least 109 records · Page 6Linked to original sources
PubMed1989

Visuo-spatial processing in parkinsonians.

It has been suggested that patients with Parkinson's disease (PDs) may have problems processing visuo-spatial information and that this deficiency may contribute to the motor control problems observed in PD. However, most studies reporting visuo-spatial deficits are equivocal; they confound perceptual and motor processes. To address this issue, the present experiment systematically compared the relative contributions of several cognitive processes to performance: perception, stimulus-response translation, movement preparation and execution. Seven non-demented PDs and seven age-matched controls performed visual RT tasks, based upon judgements of spatial displacements. Both the RT and MT data suggested that PDs do not prepare movements as adequately as normals, and that PD deficits are associated with problems controlling movement execution. On the other hand, PDs were not slower in judging distances and linking perception to action, suggesting that previous findings of visuo-spatial deficits may be due in part to motor impairments.

Aged↗
PubMed1989

Effect of gamma irradiation on the B vitamins of pork chops and chicken breasts.

A study was made of the effect of low-dose gamma irradiation on the content of thiamine (B1), riboflavin (B2), niacin, pyridoxine (B6) and cobalamin (B12) in pork chops, and thiamine, riboflavin and niacin in chicken breasts. Gamma irradiation from a caesium-137 source was used to irradiate the samples in a range of 0.49 to 6.65 kGy from -20 to +20 degrees C. Over the range of dose and temperature studied it was possible to derive a mathematical expression for predicting the losses. A calculation was made of the effect of the loss of thiamine, riboflavin and niacin due to irradiation on the overall loss of these vitamins in the American diet. The losses of riboflavin and niacin were of the order of a fraction of a per cent. Pork is an important source of thiamine, but the calculated loss at 1.0 kGy of this vitamin in cooked pork was only 1.5 per cent. There were initial increases with radiation doses up to 2-4 kGy in the measured concentrations of riboflavin and niacin in both pork and chicken. The increases were highly significant, and are of concern both to the study of radiation effects and the chemical method of the determination of these two vitamins.

Animals↗
PubMed1989

Thrombolysis with systemically administered t-PA in a new venous thrombosis model.

Early thrombosis of either the arterial or venous supply of a free flap or island pedicle flap results in total flap necrosis. Until very recently, the only option for flap salvage was surgical intervention and, often, revision of the vascular pedicle. Current advances in the pharmacologic treatment of coronary artery and deep leg vein thrombosis have kindled interest in the field of reconstructive surgery for pharmacologic treatment of thromboses that compromise flaps. In the past, there has been research on the local and systemic administration of thrombolytic agents for lysis of experimentally induced thrombi in various animal models. A new venous inversion graft thrombosis model is presented here, which possesses many advantages over previously employed research models. This study demonstrates thrombolysis with systemically administered tissue plasminogen activator (t-PA) in this model.

Animals↗
PubMed1988

Leeches. Objective monitoring of altered perfusion in congested flaps.

In plastic and reconstructive surgery, there has been new interest in the use of the medicinal leech (Hirudo medicinalis) for the treatment of venous congestion. To the best of our knowledge, no study has been performed to objectively demonstrate the benefits of leeching a congested flap. Doppler laser perfusion monitoring (DLPM) was used to record blood flow changes in pig rump flaps compromised by venous occlusion. With the application of leeches to nine congested pig rump flaps, significant increases in blood flow were demonstrated both clinically and by DLPM. It is concluded from this study that DLPM can demonstrate objective improvement in microcirculatory perfusion with leeching.

Animals↗
PubMed1988

Reconstruction of the palate using bilateral temporalis muscle flaps: a case report.

The functional deformity following removal of the maxilla is considerable. Rehabilitation used to be very difficult with prostheses or traditional flaps. Temporalis muscle flaps have been described for reconstruction following hemi-maxillectomy, but not total maxillectomy. A case is now presented to illustrate the use of bilateral temporalis muscle flaps following almost total removal of the maxilla at a Le Fort I level.

Aged↗
PubMed1988

The pectoralis major muscle flap without skin in intra-oral reconstruction.

There are many methods of reconstructing intra-oral defects following surgical treatment of cancer. A very reliable flap is the pectoralis major myocutaneous flap which has the added advantage of carotid artery protection when a radical neck dissection has also been necessary. However this flap is very bulky, may cause distortion of the female breast and there is also the problem of continued hair growth in male patients. A description of the use of the pectoralis major muscle-only flap without any overlying skin, fascia or breast tissue is given. The advantages of rapid epithelialisation within the mouth of the muscle flap together with the minimal changes to the breasts are emphasised.

Adult↗
PubMed1987

Plasma pharmacokinetics of cyclophosphamide and its cytotoxic metabolites after intravenous versus oral administration in a randomized, crossover trial.

Since cyclophosphamide is used by both oral and i.v. routes in the treatment of hematological and solid malignancies, we designed a randomized, crossover clinical trial to evaluate the pharmacokinetics of this anticancer agent after either administration route. Plasma levels of cyclophosphamide and its two cytotoxic metabolites, 4-hydroxycyclophosphamide and phosphoramide mustard, were determined in seven cancer patients randomly assigned to treatment initially with either orally or i.v. administered cyclophosphamide with a 30-day interim between alternate therapy courses. Oral treatment was used initially in five patients and i.v. treatment in two patients, and the pharmacokinetic parameter, area under the plasma disappearance curve, was determined for each metabolite in each patient for both routes of drug administration. Statistical comparison of area under the plasma disappearance curve values for this set of patients indicated no significant differences for either metabolite for oral versus i.v. drug treatment, suggesting equal efficacy for these two routes of cyclophosphamide administration.

Administration, Oral↗
PubMed1987

The duct system of the avian salt gland as a transporting epithelium: structure and morphometry in the duck Anas platyrhynchos.

The duct system of the nasal salt gland of the duck comprises central central canals, secondary ducts and main ducts. The secondary and main ducts consist of a layer of columnar cells overlying a layer of small cuboidal cells. The columnar cells have complex intercellular spaces showing evidence of Na+K+-ATPase at the apical regions. Approximately 70% of surface area of the duct system is external to the gland. During adaptation to salt water the duct system increases in size as does the gland. Although the components of the gland of adapted ducks, including the duct system within the gland, increase in size compared with normal ducks, the percentage volume densities of the components remain similar in both categories of ducks, i.e. the duct system increases in size in proportion to the glandular tissue. The volume of the duct system external to the gland is six to seven times larger than the volume within the gland. Thus, if ductal modification of secreted fluid occurs, it will be most likely to take place in the ducts external to the gland. Total surface areas of the duct system were measured from serial sections of glands and ducts from one normal and one adapted duck. These were used to calculate possible flux rates of water and sodium across the duct epithelium, assuming the occurrence of either water reabsorption of sodium secretion. Although these flux rates are high it is shown that they are similar to calculated flux rates across the luminal surface of the secretory tubules.

Animals↗
PubMed1987

Effect of NaCl, pH, temperature, and atmosphere on growth of Salmonella typhimurium in glucose-mineral salts medium.

The interactions of pH (5.0, 6.0, and 7.0), temperature (19, 28, and 37 degrees C), and atmosphere (aerobic versus anaerobic) with NaCl (0, 1, 2, 3, 4, and 5%) on the growth of Salmonella typhimurium ATCC 14028 in defined glucose-mineral salts culture medium were evaluated. Response surface methodology was used to develop equations describing the response of S. typhimurium to environmental changes. The response to an increasing concentration of NaCl at any temperature tested was nonlinear. The maximum growth was predicted to occur at an NaCl concentration of 0.5%, a temperature of 19 degrees C, and an initial pH of 7.0 under aerobic growth conditions. The relative amounts of aerobic growth at 19 degrees C, pH 7.0, and NaCl concentrations of 0, 0.5, 1, 2, 3, 4, and 5% were predicted to be 99.2, 100.0, 98.8, 90.2, 73.5, 48.6, and 15.6%, respectively. Anaerobic growth conditions repressed the amount of growth relative to that under aerobic conditions, and the effects of NaCl and pH were additive at low salt concentrations; however, at higher salt levels anaerobiosis provided protection against the effects of NaCl.

Aerobiosis↗
PubMed1987

Hepatic fatty acid profiles in aflatoxin-exposed broiler chickens.

This study was initiated to determine whether a specific fatty acid marker from hepatic lipids could be identified to confirm aflatoxin exposure in chickens. Male broiler chicks (240) were reared to 21 days of age on diets containing 0, 625, 1.25, 5.0, and 10.0 ppm aflatoxin. Live weights and organ weights differed significantly among the dietary groups. Total liver lipids increased significantly (P less than .001) with increasing aflatoxin levels. Separation of extracted lipids into neutral and polar fractions established that this increase in hepatic lipid was accounted for almost entirely by increases in neutral lipid fractions. A gain of 117% occurred in the weight of neutral lipids as aflatoxin increased from 0 to 10 ppm. In both neutral and polar lipid fractions subsequent chromatographic analysis of fatty acid methyl esters (FAME) showed linear increases in the monoenoic fatty acids with increasing aflatoxin. No single FAME from either lipid fraction was suitable for confirming aflatoxin exposure.

Aflatoxins↗
PubMed1986

Functional anatomy of the major cardiac nerves in cats.

In recognition of the extensive use of the cat as an experimental model of cardiac innervation, the effects of electrical stimulation of stellate ganglia, thoracic vagosympathetic complexes, and individual feline cardiopulmonary nerves on heart rate, blood pressure, and contractility in all four cardiac chambers were analysed and correlated with the anatomy of the thoracic autonomic nervous system. The right and left stellate ganglia in cats are relatively large and globular. Distinct dorsal and ventral ansae subclavia arise from these ganglia, connecting with the relatively small, spindle-shaped middle cervical ganglia situated in the apices of the thoracic cage bilaterally. A cranial pole nerve arises from each of the middle cervical ganglia and courses cranially to unite with the ipsilateral superior cervical ganglia. On each side, the major cardiopulmonary nerves arise from the middle cervical ganglion, the relatively large vagosympathetic trunk, and the stellate ganglion. On the right side these nerves consist of a very small right stellate cardiac nerve, a recurrent cardiac nerve, a group of craniovagal nerves and a group of caudovagal cardiopulmonary nerves. On the left side are the left stellate cardiac, ventrolateral, ventromedial, and innominate cardiopulmonary nerves. All of these nerves contain efferent parasympathetic and/or sympathetic fibers which modify cardiac chronotropism and/or inotropism. Some contain afferent fibers. These results indicate that specific cardiopulmonary nerves exist in cats, which when stimulated, modify the cardiovascular system in specific fashions.

Animals↗
PubMed1985

Independence of salt gland function and adrenocortical activity in ducks (Anas platyrhynchos).

In immature ducklings injected with hypertonic saline the volume of extrarenal salt gland secretion was unaffected by prior treatment (immediately or 4 hr before salt loading) with long-lasting adrenocorticotrophin (ACTH 100 iu/kg, im) or exogenous corticosterone (1.0 mg/kg, im). Pretreatment with metyrapone, an 11-beta-hydroxylase blocker, (80 mg/kg, im) 4 hr before salt loading did not effect the volume of salt gland secretion but delayed the onset of extrarenal excretion. Salt gland function was suppressed in birds pretreated with metyrapone immediately prior to salt loading. The intravenous administration of metyrapone after salt loading immediately reduced salt gland activity, which remained suppressed for at least 40-50 min thereafter. The inhibitory effect of metyrapone on salt gland activity was not counteracted by the subsequent or simultaneous administration of exogenous corticosterone to salt-loaded ducks. These results suggest that acute alterations in adrenocortical activity are not causally responsible for changes in salt gland function.

Adrenal Cortex↗
PubMed1985

Growth hormone secretion in anaesthetized fowl. 1. Refractoriness to repeated stimulation by human pancreatic growth hormone-releasing factor (hpGRF) or thyrotrophin releasing hormone (TRH).

The intravenous (iv) administration of thyrotrophin releasing hormone (TRH, at 1.0 or 10.0 micrograms/kg) or human pancreatic growth hormone-releasing factor (hpGRF(1-44)NH2, at 10 micrograms/kg) markedly increased the growth hormone (GH) concentration in the plasma of immature or adult cockerels anaesthetized by sodium pentabarbitone (30 mg/kg, iv). A second injection of either TRH or hpGRF failed to increase the GH concentration in immature chicks when administered 15, 30, or 60 min after the first injection. However, significant GH responses to TRH or hpGRF were observed when the interval between injections was either 120 or 240 min. The magnitude of the GH responses to TRH were, however, diminished by 83.3 and 26.7% when given 120 or 240 min after the initial TRH injection, and the responses to hpGRF were similarly reduced by 68.3 and 33.6%. A similar period of GH refractoriness to TRH or hpGRF stimulation was also observed in adult birds, although the recovery of GH responsiveness occurred earlier. While a second injection of hpGRF was ineffective in increasing the plasma GH concentration if given within 30 min of the first, it was fully effective when the interval between injections was greater than 60 min. In response to a second injection of TRH, the GH concentration was elevated when the interval between injections was greater than 120 min, after which the magnitude of the response evoked was greater than that induced by the initial injection. Growth hormone secretion secretion in immature and adult fowl is therefore refractory to repeated provocative stimuli, although the mechanism involved is unknown.

Anesthesia↗