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Biomedical subjects

P H Cox

Publications and source records attributed to P H Cox.

At least 19 recordsLinked to original sources
PubMed1992

Spectral content as a cue to perceived auditory distance.

Changes in the spectral content of wide-band auditory stimuli have been repeatedly implicated as a possible cue to the distance of a sound source. Few of the previous studies of this factor, however, have considered whether the cue provided by spectral content serves as an absolute or a relative cue. That is, can differences in spectral content indicate systematic differences in distance even on their first presentation to a listener, or must the listener be able to compare sounds with one another in order to perceive some change in their distances? An attempt to answer this question and simultaneously to evaluate the possibly confounding influence of changes in the sound level and/or the loudness of the stimuli are described in this paper. The results indicate that a decrease in high-frequency content (as might physically be produced by passage through a greater amount of air) can lead to increases in perceived auditory distance, but only when compared with similar sounds having a somewhat different high-frequency content, ie spectral information can serve as a relative cue for auditory distance, independent of changes in overall sound level.

Acoustic Stimulation↗
PubMed1992

A quantitative index derived from 99mTc-pertechnetate scintigraphy to assist in the diagnosis of primary Sjögren's syndrome.

A safe and simple technique is reported by which primary Sjögren's syndrome can be detected with a relatively high specificity and sensitivity. The method of serial scintigraphy has been used with reasonable success; however, the application of the linearity index as described here produced superior results. In 71 patients investigated, a sensitivity of 87% and specificity of 93% were recorded and make this the method of choice for evaluating patients suspected of having primary Sjögren's syndrome.

Humans↗
PubMed1992

Acute improvement of cardiac function with intravenous L-propionylcarnitine in humans.

As the myocardial carnitine content, a key control factor in myocardial oxidative metabolism and energy transfer, is reduced in heart failure, administration of L-propionylcarnitine (LPC), a potent analogue of L-carnitine, potentially may improve cardiac function, possibly through a positive inotropic effect. As its hemodynamic profile is unknown in humans, 32 fasting normotensive patients with coronary artery disease received either 15 mg/kg of LPC (n = 16) or vehicle (mannitol/acetate, n = 16) infused over 5 min. Hemodynamic, radionuclide [peak ejection and filling rates (PER and PFR, respectively)], and metabolic variables (myocardial O2, lactate, and carnitine uptake) were studied at baseline and 1, 3, 5, 10, 15, and 45 min postdrug. The baseline ejection fraction was depressed in LPC patients (40 +/- 3% vs. 48 +/- 4% in the vehicle group, p less than 0.05) as a result of a significant high incidence of previous infarctions. Immediately following LPC, the cardiac total carnitine uptake changed from 102 +/- 181 to 5,335 +/- 1,761 mumol/L (p less than 0.05). In both groups, left ventricular systolic and end-diastolic pressures increased significantly by 5 and 20%, respectively, during the first 5 min. In the vehicle group, contractility decreased by 5%, accompanied by a significant 11% fall in the stroke volume. In contrast, following LPC, isovolumetric contractility indices remained unaltered. Instead, both the PER and PFR improved by 16% at 45 min. Moreover, the cardiac output increased by 8%. LPC did not affect systemic or coronary hemodynamics. Lactate uptake increased by 42%, but myocardial O2 consumption did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

A comparison of the effectiveness of three regimens in the prevention of Pneumocystis carinii pneumonia in human immunodeficiency virus-infected patients.

BACKGROUND: Pneumocystis carinii pneumonia (PCP) is a major cause of morbidity and the leading cause of death in patients with the acquired immunodeficiency syndrome. The prevention of the occurrence and recurrence of PCP is a cornerstone in the treatment of patients infected with the human immunodeficiency virus. There are few studies comparing PCP prophylactic regimens. METHODS: The efficacy of three regimens for prophylaxis against PCP was assessed in a retrospective chart review of 211 human immunodeficiency virus-infected patients at risk for the disease. Over the course of the 2-year study period, 133 patients were prescribed trimethoprim-sulfamethoxazole (one double-strength tablet twice a day, thrice weekly) for a mean of 7.4 months (range, 1 to 25 months). Seventy-seven patients received dapsone (50 mg daily) for a mean of 5.7 months (range, 1 to 23 months), and 125 patients received aerosolized pentamidine (300 mg via nebulizer once monthly) for a mean of 9.3 months (range, 1 to 21 months). The majority of patients (62%) received primary prophylaxis; 38% had one or more previous episodes of PCP; and 73% were receiving concomitant antiretroviral therapy. RESULTS: Pneumocystis carinii pneumonia did not develop in any patient receiving trimethoprim-sulfamethoxazole in 981 patient-months. Five patients receiving dapsone for 437 patient-months and 17 patients receiving aerosolized pentamidine for 1166 patient-months developed PCP. Fifty-six percent of the trimethoprim-sulfamethoxazole group and 55% of the dapsone group changed drug due to adverse reactions, while only 2% in the aerosolized pentamidine group required drug change. CONCLUSION: Despite its adverse reaction profile, trimethoprim-sulfamethoxazole is the most effective agent to prevent the occurrence and recurrence of PCP.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Uterine radiation dose from open sources: the potential for underestimation.

The evaluation of the risk of radiation damage to the unborn child as the result of the administration of radionuclides remains a subject for discussion (Mountford 1989). Lack of information concerning the biodistribution of radiopharmaceuticals in the early stages of pregnancy, before organogenesis has occurred, has greatly restricted the objective assessment of fetal doses. Recent observations on the biodistribution of a therapeutic dose of sodium iodide 131 in a patient with an unsuspected early pregnancy lead us to suspect that current dose estimates with respect to uterine exposure (ARSAC 1988) may seriously underestimate the actual exposure of the developing fetus.

Abnormalities, Radiation-Induced↗
PubMed1990

Outcomes of treatment with AZT of patients with AIDS and symptomatic HIV infection.

Although many experimental treatments are being evaluated for the treatment of acquired immunodeficiency syndrome (AIDS) and symptomatic HIV infection (ARC), only zidovudine (AZT) has been shown to prolong the lives of such patients. This article reviews the authors' experience with 101 patients with AIDS (73) or ARC (28) treated with AZT at a public hospital clinic in Los Angeles County. The patients were seen at least monthly for five to 87 weeks (means = 27.6) by nurse practitioners and physicians. Initiation of AZT therapy required a CDC-defined diagnosis of AIDS or an absolute CD4 lymphocyte cell count of 200/mm3 or less. The demographic distribution of the patient population was as follows: Caucasian, 59; Hispanic, 22; and black, 20. The mean age of the population was 37.4 years, and the predominant risk factor was homosexual contact (76 percent). Forty-one patients required modification of their AZT doses secondary to anemia, neutropenia, a combination of anemia and neutropenia, or for personal reasons. Thirty-four of the 41 patients (83 percent) never returned to full dose after reductions. The majority of these patients (81 percent) had AIDS and/or CD4 lymphocyte counts less than 150/mm3. Hematologic toxicity was common; 27 percent required blood transfusions. Of the 101 patients followed from five to 87 weeks, 87 percent were surviving after a mean of 45 weeks of AZT therapy. The article underscores the effectiveness of AZT in prolonging the lives of AIDS and ARC patients.

AIDS-Related Complex↗
PubMed1988

Indium 111 antimyosin for the detection of leiomyosarcoma and rhabdomyosarcoma.

111In-antimyosin monoclonal antibody complex passes through damaged myocardial cell membranes and binds to the intracellular myosin. Normal myocardial and other muscle cells show no uptake. Rhabdomyosarcoma and Leiomyosarcoma cells also contain intracellular myosin and the cell membrane permeability is greater than normal. Significant uptake of 111In-antimyosin was observed in patients with Leiomyosarcoma and Rhabdomyosarcoma suggesting that the reagent has a potential for the in vivo detection of these tumour types. Tumour to background ratios of 10:1 were measured in one case and in view of the fact that the site of accumulation is intracellular, antimyosin may have a potential as a carrier for therapeutic agents.

Adult↗
PubMed1988

The stability of 99mTc-DTPA and 99mTc-HIDA following ultrasonic nebulisation.

The stability of 99mTc-DTPA (diethylenetriamine-pentaacetic acid) and 99mTc-HIDA (2,6-diethylacetanilido-iminodiacetic acid) were evaluated following ultrasonic nebulisation. The results confirm that either of these radiopharmaceuticals can be used in our nebuliser without significant radiochemical breakdown.

Drug Stability↗
PubMed1987

A high efficiency ultrasound nebuliser for radioaerosol studies of the lungs.

An ultrasound nebuliser with variable delivery temperature and nebulisation volume was tested for particle size distribution, efficiency, and application in a clinical environment. The results obtained comply with our criteria for a general purpose radioaerosol generating system for use in evaluating various parameters of lung function.

Humans↗
PubMed1987

Dosimetric consequences of interstitial extravasation following i.v. administration of a radiopharmaceutical.

The worst case radiation dose to tissue due to inadvertent intravenous injection of a radiopharmaceutical was estimated for the most commonly utilised radioisotopes. The probability of radiation injury induction was examined for the various radionuclides considering the maximal specific activity values encountered in diagnostic practice. A possible approach to the management of incidents involving extravasal activity deposition is discussed.

Extravasation of Diagnostic and Therapeutic Materi↗
PubMed1987

A comparative study of myocardial infarct detection using Tc99m pyrophosphate and In111 DTPA antimyosin (R11D10 Fab).

A crossover study to examine the potential of In111 antimyosin Fab fragment to detect fresh myocardial infarcts in comparison with Tc99m pyrophosphate is reported. In 27 cases indium antimyosin correctly diagnosed 19 patients with infarcts and 4 true negatives. There were also 2 false positive and 2 false negative scintigrams. Tc99m pyrophosphate detected 21 infarcts and 6 true negatives correctly.

Diphosphates↗
PubMed1977

Technetium-99m-labelled diethyl-acetanilido-iminodiacetate: a new hepatobiliary agent. A preliminary report.

A new hepatobiliary reagent 99Tcm diethyl-acetanilido-iminodiacetate has been examined in a small group of patients to evaluate its potential as a clinical reagent. The radiopharmaceutical accumulated readily in the hepatocytes and was rapidly excreted via the biliary system. It would appear possible to develop a dynamic test of hepatocyte function coupled with an evaluation of the patency of the biliary system. No adverse reactions were observed.

Acetanilides↗
PubMed1976

Bone scanning.

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Bone Neoplasms↗
PubMed1976

The correlation between liver scintigraphy and serum CEA levels in the detection of liver metastases from rectum carcinoma. A retrospective study.

Radiocolloid liver scintigraphy for the detection of liver metastases is widely used. Because of the known limitations of this technique we investigated the correlation between liver scintigraphy and serum CEA levels in patients with a confirmed diagnosis of primary rectum carcinoma. The serum CEA level is not suitable as a screening test for cancer, but it can be helpful as an extra parameter for the detection of liver metastases. The correlation between liver scintigraphy, the serum CEA level and the clinical findings has also been studied. A good correlation between liver scintigraphy and the serum CEA level was found. Serum CEA levels can be helpful in facilitating the evaluation of liver scintigraphy in patients with carcinoma of the rectum.

Carcinoembryonic Antigen↗