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Biomedical subjects

A Parker

Publications and source records attributed to A Parker.

At least 145 records · Page 8Linked to original sources
PubMed1989

A comparison of morphine, meperidine, and oxymorphone as utilized in patient-controlled analgesia following cesarean delivery.

Seventy-five patients (n = 75) undergoing elective cesarean delivery during epidural anesthesia were randomly assigned to receive one of three opioid analgesics via patient-controlled analgesia (PCA) when they first complained of pain in the recovery room. Following administration of an analgesic loading dose, patients were allowed to self-administer morphine 1.8 mg, meperidine 18 mg, or oxymorphone 0.3 mg iv every 8 min as required. Data collected during the 24-h observation period included visual analog scale (VAS) pain scores at rest and during movement, VAS patient satisfaction scores, total drug administered, the ratio of attempts/injections, and the incidence of nausea/vomiting, sedation, and pruritus. After adjusting for narcotic potency, no differences in 24-h dose requirements were noted between treatment groups (NS). All patients achieved an excellent level of analgesia at rest (NS); however, onset was most rapid with oxymorphone (P less than 0.05). The percentage of patients reporting severe pain during movement was highest in the meperidine group (P less than 0.05). Oxymorphone was associated with the highest incidence of nausea and vomiting (P less than 0.05), whereas increased sedation and pruritus were noted with morphine. Patient satisfaction with drug effect demonstrated significant negative correlations with resting pain scores and degree of sedation. Whereas morphine is a more commonly utilized PCA analgesic, the excellent analgesia, low incidence of sedation, and high patient satisfaction provided by meperidine and oxymorphone suggested useful alternatives.

Adult↗
PubMed1989

Effect of bronchial challenge on breathing patterns and arterial oxygenation in stable asthma.

The effect of histamine or methacholine inhalational challenge on breathing patterns and oxygen saturation was investigated in ten stable asthmatic patients. We used the respiratory inductive plethysmograph to record respiratory timing and minute ventilation along with an ear oximeter to measure oxygen saturation (SaO2). As FEV1 fell during the challenge procedure, SaO2 also fell (average 3 percent). Furthermore, with histamine challenge, expiratory time (Te), inspiratory time (Ti), and breath period (Ttot) all increased; minute ventilation probably also fell. These changes in breathing pattern and SaO2 were reversed by inhalation of a beta 2-agonist. However, no such changes in breathing patterns were observed with methacholine challenge despite a similar fall in FEV1. Bronchial challenge produces hypoxia in stable asthmatic patients, which might result from a combination of hypoventilation with alteration in alveolar ventilation/perfusion relationships.

Adolescent↗
PubMed1988

Surgery of the tonsils and adenoids in relation to secretory otitis media in children.

One hundred and fifty children aged between 2 and 9 years with bilateral SOM were allocated at random to three groups: Adeno-tonsillectomy (47 cases), adenoidectomy (47 cases) and neither procedure (53 cases). A further 42 children were allocated to either adenoidectomy or no surgery. In all only one ear was treated at random by myringotomy and insertion of a ventilation tube. The unoperated ear was examined six weeks, six months, nine months, one, two and three years post-operatively for otoscopic clearance of the effusion, impedance change and improvement in mean hearing threshold. Thus the effects on middle ear status of adenoidectomy alone and in combination with tonsillectomy were assessed. There was a significant clearance of middle ear fluid, change from no peak to peak impedance measurement and hearing gain as a result of both procedures with a late trend favouring the combined operation. Neither pre-operative tonsils size nor the number of attacks of tonsillitis affect outcome. However there is a relationship between age and radiographic post-nasal space airway size with clearance of the effusion one year after surgery. These findings permit recommendation for adenoidectomy with improved expectation for resolution of SOM if cases are selected with reference to these two variables. They also suggest in which cases the operation should not be recommended. Despite the trends in outcome favouring combined operations, the extra morbidity associated with the addition of tonsillectomy does not at present justify recommendation for removal of the tonsils in addition to adenoidectomy for cases with SOM. Tonsillectomy in these children should be assessed on grounds of tonsillar pathology per se and not on the status of the middle ear.

Acoustic Impedance Tests↗
PubMed1986

A comparison of preoperative exfoliative cervical cytology with subsequent histology.

A comparison of the preoperative cervical cytology with the subsequent histology in 441 cases showed a wide variation in the prediction of the histological diagnoses by cytology. There was a precise correlation in 66% of cases. The false negative rate was 11.5% and the false positive rate was 11.2%. These data illustrate the difficulty managing premalignant and malignant disease of the uterine cervix using cytology alone for guidance.

Biopsy↗
PubMed1985

Capabilities of monkey cortical cells in spatial-resolution tasks.

The performance of individual neurons in monkey striate cortex has been examined in three spatial-resolution tasks by making microelectrode recordings from single cells in anaesthetized, paralyzed animals. The statistical reliability of responses from cells was used to estimate threshold levels of performance. For each task (resolution acuity for high-contrast gratings, discrimination of gratings varying in spatial frequency, and localization ability, i.e., discrimination of spatial phase), performance approaching psychophysical thresholds was obtained from single cortical cells. The receptive-field organization underlying localization performance was examined in detail by the use of a linear model that relates localization ability to the sensitivity of the receptive field to luminance contrast. Calculations from this model agree well with direct measurements of localization performance and are comparable with psychophysical measurements of hyperacuity. Though it has been suggested that cells with nonoriented receptive fields in cortical layer IVc beta may be responsible for recovering fine-grain spatial information, our calculations indicate that these cells are poorer at localization than many other cells in the cortex.

Animals↗
PubMed1983

The effects of temporal modulation on the perceived spatial structure of sine-wave gratings.

Evidence is presented that two distinct effects are generated when a sine-wave grating is temporally modulated. These effects may differentiated on the grounds of different responses with different forms of temporal modulation (drift or phase reversal), different behaviour with changes of visual eccentricity and with changes of contrast. One effect is roughly equivalent to spatial-frequency doubling, as described by Kelly. The other is seen as a fractional increase in apparent spatial frequency ie 1.2 X 1.4 X the original. Earlier papers are reviewed to lend support to these conclusions. The results obtained for spatial-frequency doubling are consistent with Kelly's model of a nonlinearity followed by a temporal integration. Spatial-frequency doubling emerges under conditions where a fractional increase in apparent spatial frequency would generally be expected but the particular spatiotemporal conditions are such that a breakdown in the motion-correspondence process may be suspected. Reasons for the existence of fractional shifts are not entirely clear, but it is argued that the similarity of the shifts induced by various manipulations (decreases of luminance, decreases of contrast, temporal modulation) are such that a general explanation must be sought, rather than one specific to temporal modulation alone.

Adult↗
PubMed1981

The meaning of attempted suicide to young parasuicides: a repertory grid study.

In an attempt to clarify the intentional aspect of parasuicide, constructs in response to a supposed crisis were elicited from a group of overdose patients, using the standard method of contrasting elements. In this case the elements were presented as a list of 11 alternative behaviours (including overdose and suicide) possible in such a situation. Using 9 of the most common constructs obtained, a repertory grid was administered to a second group of overdose patients and by computer analysis consensus group grids were obtained for patients scoring high and low on the Beck suicidal intent scale. These consensus grids showed that the low intent group perceived an overdose (in comparison to other alternative behaviours) as similar to 'being alone and crying' and 'getting drunk' and construed it almost exclusively as an escape from tension. In contrast, the high intent group perceived overdose and suicide in quite similar terms. The data indicated that an overdose may have a respite function for low suicidal intent patients.

Adolescent↗
PubMed1980

Degenerative myelopathy in a cat.

Degenerative myelopathy was diagnosed in a 6-year-old cat that had progressive ataxia, posterior paresis, and loss of conscious proprioception over a period of 8 months. Corticosteroid therapy did not alleviate clinical signs, and the cat was euthanatized. Microscopic examination of the spinal cord revealed diffuse degeneration of myelin attended by marked astrocytosis. The degenerative changes were most marked in the thoracolumbar segment. The cause of the degenerative lesions was not apparent.

Animals↗
PubMed1980

Exocrine pancreatic secretion in rats treated with reserpine after stimulation with pilocarpine, dopamine, and caerulein.

Pancreatic juice was collected in vivo from control and reserpine-treated rats after stimulation with pilocarpine (0.2 mg/100 g body weight), dopamine (6--7 mg/100 g body weight), caerulein (90--100 pmole total dose) or with a combination of caerulein and secretin (6 u/100 g body weight) and the volume, amylase, bicarbonate and chloride outputs were compared. The results indicate that the secretory response to the three secretagogues was significantly reduced in the drug treated animals. Thus, the volumes of pancreatic juice were 57.0, 60.5, and 15.7% of those obtained in control rats after stimulation with, respectively, pilocarpine, dopamine, and caerulein. Amylase output was 63.8, 67.1, and 21.0% and bicarbonate output was 29.9, 46.8, and 6.2% of those observed in untreated rats after the same stimulants. Fluid secretion increased in the treated animals to 71.3% of that of controls when both caerulein and secretin were administered together and amylase output became greater than in control rats (151%). However, bicarbonate output was still 55.2% of that of controls with this combined stimulation. It is concluded that chronic reserpine administration impairs exocrine pancreatic secretion and that this effect involves both the acinar and ductal portions of the gland. This impairment involves the physiologic responses of these two segments of the glandular epithelium to both neural and hormonal stimulants. These findings suggest that the exocrine pancreatic disturbance in reserpine-treated rats may be similar to that observed in cystic fibrosis (CF), and because the treated rat has been proposed as a model for the human disease, they suggest the use of this model as a test system for the study of the pancreatic secretory abnormality in CF.

Amylases↗
PubMed1978

Endometrial factors under treatment with oestrogen and oestrogen/progestogen combinations.

In a continuing prospective study, uterine curettage was undertaken on sixty-four patients attending a Menopause Clinic prior to consideration of gonadal hormone therapy. Two of these patients (3.1%) were found to have endometrial hyperplasia, and subsequently they were not given gonadal hormone therapy. Sixty-two patients with normal endometrium at pre-treatment curettage received cyclical oestrogen regimens or sequential oestrogen/progestogen treatments. Four (30.8%) of the thirteen patients in receipt of cyclical 'high-dose' oestrogens developed cystic glandular hyperplasia, whereas none of the patients taking either cyclical 'low-dose' oestrogens (thirty patients) or cyclical-sequential oestrogen/progestogen regimens (nineteen patients) developed endometrial hyperplasia. Among the patients with a normal endometrium, both before and during cyclical gonadal hormone therapy, regular withdrawal bleeding was experienced by thirty-two patients (51.6%). Breakthrough bleeding occurred in nine (14.5%), while twenty-one patients (33.9%) had no vaginal bleeding. Of the four patients with normal endometrium at pre-treatment curettage who subsequently developed endometrial hyperplasia during cyclical 'high-dose' oestrogen therapy, regular withdrawal bleeding was experienced by two patients, and in one of these breakthrough bleeding also occurred. Furthermore, in the four patients who developed endometrial hyperplasia, this condition occurred within six months in two patients and within 9 and 10 months respectively in the remaining two. In the nineteen patients receiving cyclical sequential oestrogen/progestogen regimens, all had regular withdrawal bleeding, while one patient had breakthrough bleeding during sequential therapy. It is concluded that in those climacteric patients who present with severe menopausal symptoms which necessitate the administration of high-dose oestrogen regimes it is necessary either to undertake both pretreatment uterine curettage or to add a progestogen to the oestrogen in a sequential regimen.

Climacteric↗
PubMed1977

Improved quality of packed cells.

Improved viability, quality, oxygen delivery capacity and metabolic activity of packed cells was obtained when blood was collected into (CP2D) citrate-phosphate anticoagulant with extra dextrose and, after separation of plasma, stored in an adenine-enhanced electrolyte solution. The system has been incorporated into clinical transfusion practice.

Adenosine Triphosphate↗