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Biomedical subjects

H Royal

Publications and source records attributed to H Royal.

15 recordsLinked to original sources
PubMed1996

Importance of radon as a threat to public health.

Since the discovery of x rays, the public has shown increasing concern about exposure to radiation. In the mid-1980s, with the dissemination of information about the ubiquitous nature of radon, this concern about radiation exposure has taken on a new perspective. As the general public realizes that exposure to radiation is an unavoidable part of life, questions arise as to how much exposure is acceptable when weighed against the costs of reducing the exposure. Because limited resources are available to protect the public's health and the environment, these resources need to be used wisely. The cost-effectiveness of the various options to lessen the potential adverse health effects from radon must be considered.

Air Pollutants, Radioactive↗
PubMed1995

Laparoscopic pneumodissection: a unique means of tissue dissection.

PURPOSE: To study the acute and chronic tissue effects of using high pressure CO2 to dissect tissues during laparoscopic procedures. MATERIALS AND METHODS: A 5-mm. laparoscopic pneumodissector, capable of delivering brief bursts of high pressure CO2 (20 to 100 psi), was discharged on a variety of porcine tissues including the renal hilum. Acute and chronic histological sections, intraoperative blood gases and perioperative renal scans were obtained. RESULTS: The only tissue with significant acute damage was the spleen. Acute changes in other tissues were minimal; long-term studies revealed no discernible damage to these same tissues. Intraoperative blood gases revealed no significant changes in the serum pCO2 or pH. Likewise, there was no renal damage discernible by renal scans. CONCLUSIONS: Pneumodissection at 50 psi is a safe method for dissecting the porcine kidney and the vessels of the renal hilum. Clinical studies are pending.

Animals↗
PubMed1994

Radon update: facts concerning environmental radon: levels, mitigation strategies, dosimetry, effects and guidelines. SNM Committee on Radiobiological Effects of Ionizing Radiation.

The risk from environmental radon levels is not higher now than in the past, when residential exposures were not considered to be a significant health hazard. The majority of the radon dose is not from radon itself, but from short-lived alpha-emitting radon daughters, most notably 218Po(T1/2 3 min) and 214Po (T1/2 0.164 msec) along with beta particles from 214Bi (T1/2 19.7 min). Radon gas can penetrate homes from many sources and in various fashions. Measuring radon in homes is simple and relatively inexpensive and may be accomplished in a variety of ways. Although it is not possible to radon-proof a house, it is possible to reduce the level. In high radon areas, if the average level is higher than 4-8 pCi/liter (NCRP recommended level is 8 pCi/liter; EPA recommended level is 4 pCi/liter), appropriate action is advised. The shape of the dose response curves for miners exposed to alpha-emitting particles in the workplace is consistent with current biologic knowledge. It is linear in the low dose range and saturates in the high dose range. No detectable increase in lung cancer frequency is seen in the lowest exposed miners (those with exposures < 120 WLM, the relevant dose interval for most homes). Evidence for a health effect from radon exposure is based on data from animal studies and epidemiologic studies of mines. Extensive radiobiologic data predict a linear dose-response curve in the low dose region due to poor biological repair mechanisms for the high density of ionizing events that alpha particles create. However, no compelling evidence for increased cancer risks has yet been demonstrated from "acceptable" levels (< 4-8 pCi/liter).

Air Pollutants↗
PubMed1990

Intestinal permeability in gastrointestinal disorders. Use of oral [99mTc]DTPA.

This study examined intestinal permeability in gastrointestinal disorders by measuring urinary recovery following oral administration of [99mTc]DTPA in 117 subjects. The mean percent of the ingested dose excreted in a 24-hr urine sample was 2.8 +/- 1.6% in 11 healthy controls, 10.8 +/- 10.2% (P less than 0.001) in 21 ulcerative colitis patients, 8.0 +/- 4.7% (P less than 0.001) in 35 Crohn's disease patients, 5.1 +/- 2.9% (P less than 0.01) in 17 patients with heterogeneous digestive disease diagnoses, and 3.2 +/- 4.7% (P greater than 0.05) in 33 patients with hepatobiliary diagnoses. Among ambulatory patients, Crohn's disease subjects, but not ulcerative colitis patients, had greater urinary recovery than the controls (P less than 0.05). The Crohn's disease activity index correlated positively with the radionuclide recovery in Crohn's subjects (r = 0.455, P less than 0.02). In a heterogeneous sample of subjects simultaneous ingestion of [99mTc]DTPA and [51Cr]EDTA produced urinary levels that were correlated positively (r = 0.556, P less than 0.001). Increased absorption of [99mTc]DTPA relative to [51Cr]EDTA, however, was noted in ulcerative colitis patients (P less than 0.05). In conclusion, increased intestinal permeability has been demonstrated by utilizing [99mTc]DTPA in Crohn's disease and ulcerative colitis patients. Although this observation appears to be a nonspecific indicator of injury, the test provides a simple objective means of establishing disease activity, which possibly may be utilized for therapeutic and investigative studies.

Administration, Oral↗
PubMed1984

Hypogonadism, hyperprolactinaemia, and temporal lobe epilepsy in hyposexual men.

Previously unrecognised temporal lobe epilepsy (TLE) was diagnosed in 11 of 16 hyposexual men. 6 had neuroendocrine abnormalities (hypogonadism in 4 and hyperprolactinaemia in 2). 4 men with hypogonadism and TLE had persistently subnormal serum testosterone, with a blunted luteinising hormone (LH) response to luteinising hormone releasing hormone (LHRH) in 2 and, in these men, unlike those with isolated hypogonadism, there was no improvement in libido or potency when parenteral testosterone was given. Men with TLE and hyperprolactinaemia had normal serum testosterone and an enhanced serum LH response after LHRH, but effective doses of the dopaminergic agonists, bromocriptine or pergolide, did not produce sustained normoprolactinaemia. In the men with neuroendocrine dysfunction and TLE the most effective therapeutic sequence was first to treat the epilepsy with anticonvulsants and then to add appropriate neuroendocrine therapy. In 2 men hormone levels became normal and sexual function was restored on anticonvulsant therapy alone.

Adult↗
PubMed1984

Left ventricular pressure-volume diagrams and end-systolic pressure-volume relations in human beings.

Assessment of left ventricular pressure-volume relations serially in response to altered loading conditions and heart rate has been difficult to achieve with contrast ventriculography. Accordingly, to study changing pressure-volume relations during altered loading and heart rate, left ventricular pressure and radionuclide absolute volume curves (obtained using a counts-based method with attenuation factor corrections) were recorded in 20 patients. Ventricular pressure and radionuclide volume curves were digitized and synchronized to end-diastole, and pressure-volume plots were subsequently constructed from 32 pressure-volume coordinates throughout the cardiac cycle. In all patients, the correlation between radionuclide absolute volumes and angiographic ventricular volumes was r = 0.92. In 10 patients in whom both radionuclide and angiographic pressure-volume diagrams were constructed, the agreement between the two methods was excellent. With this method, end-systolic pressure-volume relations were examined during altered left ventricular loading conditions, pacing-induced incremental increases in heart rate and pacing-induced ischemia. Using pharmacologically induced changes in left ventricular loading conditions, the slope and volume intercept of the end-systolic pressure-volume line could be calculated as a means of assessing basal contractility. During pacing-induced tachycardia, the slope and volume intercept of the end-systolic pressure-volume line could be calculated to quantify the Treppe effect and assess negative inotropic changes secondary to ischemia. This study supports the validity of using serial recordings of left ventricular pressure and radionuclide volumes to assess left ventricular pressure-volume relations, and indicates that this approach may be useful in the analysis of end-systolic pressure-volume relations in patients.

Cardiac Pacing, Artificial↗