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Biomedical subjects

A Meyers

Publications and source records attributed to A Meyers.

At least 19 recordsLinked to original sources
PubMed2004

Sparing of the penile bulb and proximal penile structures with intensity-modulated radiation therapy for prostate cancer.

Quality of life is an important consideration in the treatment of early prostate cancer. Laboratory and clinical data suggest that higher radiation doses delivered to the bulb of penis and proximal penile structures correlates with higher rates of post-radiation impotence. The goal of this investigation was to determine if intensity-modulated radiation therapy (IMRT) spares dose to the penile bulb while maintaining coverage of the prostate. 10 consecutive patients with clinically organ confined prostate cancer were planned with 3D conformal radiation therapy (3D-CRT) or IMRT to give a dose of 74 Gy without specifically constraining the plans to spare the penile bulb. All 10 patients were ultimately treated with IMRT. Dose-volume histograms were evaluated and the doses to prostate, rectum, bladder and penile bulb were compared. IMRT reduced the mean penile bulb doses compared with 3D-CRT (33.2 Gy vs 48.9 Gy, p<0.001), the percentage of penile bulb receiving over 40 Gy (37.7% vs 67.2%, p<0.001) and the dose received by >95% of penile bulb (5.3 Gy vs 11.7 Gy, p=0.003). Maximum penile bulb doses were higher with IMRT (81.2 Gy vs 73.1 Gy, p<0.001) although the volume of this high dose region was small. Both methods resulted in similar coverage of the prostate. The volume of rectum receiving 70 Gy was significantly reduced with IMRT (18.4% vs 21.9%, p=0.003) but the volumes of bladder receiving 70 Gy were similar (p=0.3). IMRT may potentially reduce long term sexual morbidity by reducing the dose to the majority of the penile bulb.

Dose-Response Relationship, Radiation↗
PubMed2001

Recurrent renal stone disease-advances in pathogenesis and clinical management.

Kidney stones are common in industrialised nations: up to 15% of white men and 6% of all women will develop one stone, with recurrence in about half these people. Risk factors for formation of stones include urinary promoters (calcium, urate, cystine, and sodium) and urinary inhibitors (magnesium, citrate, and nephrocalcin). Acute renal colic can be precipitated by dehydration and reduced urine output, increased protein intake, heavy physical exercise, and various medicines. Such colic manifests as severe loin pain and can be accompanied by frequent urination, dysuria, oliguria, and haematuria. Documentation of stone characteristics is extremely important: type, size, location, and underlying metabolic abnormalities. Such details can be obtained with a combination of biochemical investigations, microscopic examination of urine under polarised light, and an intravenous pyelogram. Ultrasonography and plain abdominal radiographs are also useful, especially for patients unable to tolerate an intravenous pyelogram. Acute therapy includes complete pain relief, rehydration, and encouragement of diuresis. Long-term management encompasses education of patients with regard to diet and fluid intake, control of calciuria, citrate replacement, and treatment of any underlying urinary-tract infection or metabolic abnormality. Stones smaller than 5 mm normally pass spontaneously, whereas larger stones, as big as 2 cm, are best treated with extracorporeal shock-wave lithotripsy. All physicians should have a clear understanding of the pathogenesis and clinical management (acute treatment and prevention of recurrence) of renal stone disease.

Acute Disease↗
PubMed2001

What's in a name.

Explore the source record for details and available documents.

Communication↗
PubMed2001

Thymic size on chest radiograph and rapid disease progression in human immunodeficiency virus 1-infected children.

BACKGROUND: Early infection of the thymus, an organ central to the ontogeny of the immune system, has been proposed as a cause of rapid progression in pediatric HIV disease. OBJECTIVE: To test the hypothesis that small thymic volume is associated with rapid disease progression in HIV-infected children. DESIGN: Three pediatric radiologists established criteria for rating the size of the thymic profile on chest radiographs. All available baseline chest radiographs were reviewed in a random sequence, with radiologists blinded to study subjects' clinical status. A consensus was reached on whether the thymus was normal or small for age. SETTING: A prospective multicenter study of the natural history of HIV-1 infection in children, the Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted Human Immunodeficiency Virus Infection (P2C2) Study. PATIENTS: Fifty-eight HIV-infected children and 38 control children (uninfected but born to HIV-infected women) for whom chest radiographs in the first year of life were available. MAIN OUTCOME MEASURE: Rapid progression of HIV disease, defined as CDC Clinical Category C (severely symptomatic) or Immunologic Category 3 (severe immunosuppression) by 1 year of age. RESULTS: The mean age at the time of chest radiography was 3.5 months. Ten (17%) HIV-infected children had reduced thymic profile size, whereas no controls did (P = 0.006). Of the 58 (59%) HIV-infected children 34 were classified as rapid progressors, and 9 (26%) of them had reduced thymus size, compared with 1 (4%) of the non-rapid progressor children [odds ratio, 8.28; 95% confidence interval (CI), 1.0, 70.5; P = 0.035]. Baseline mean CD4+ count was 1642 (95% CI 1322 to 2009) cells/microl for those with normal thymus and 740 (95% CI 380 to 1275) cells/microl for those with reduced thymus (P = 0.007). CONCLUSION: Early thymic involution is associated with rapidly progressive disease in HIV-infected children.

Adolescent↗
PubMed2000

Derivatives of glutamic acid as new surfactants.

Starting from glutamic acid, different types of surfactants have been synthesised by using original trimodular strategies. Monosubstituted zwitterionic amides of glutamic acid obtained with excellent yields show good surface activity. The grafting of a second hydrophobic side-chain leads to bicatenar cationic surfactants or to disubstituted nonionic cyclic compounds. In order to reduce the hydrophobic character of the bicatenar surfactants, a second synthetic method has been developed, allowing the introduction of a polar sugar group into these molecules. The surfactant properties of several of the products have been determined by physico-chemical methods such as surface tension measurements and compression isotherm studies by means of a Langmuir balance.

Alcohols↗
PubMed2000

Distribution and characterization of GFP(+) donor hematogenous cells in Twitcher mice after bone marrow transplantation.

The twitcher mouse is a murine model of globoid cell leukodystropy, a genetic demyelinating disease caused by a mutation of the galactosylceramidase gene. Demyelination of the central nervous system commences around 20 postnatal days. Using GFP-transgenic mice as donors, the distribution of hematogenous cells after bone marrow transplantation was investigated in the twitcher mice. Bone marrow transplantation was carried out at 8 postnatal days. In twitcher chimeric mice examined before 30 postnatal days, numerous GFP(+) cells were detected in spleen and peripheral nerve but only a few were detected in the liver, lung, and spinal white matter. In contrast, at 35 to 40 postnatal days when demyelination is evident, many GFP(+) cells with ameboid form were detected in the white matter of the spinal cord, brainstem, and cerebrum. Approximately half of these GFP(+) cells were co-labeled with Mac-1. In twitcher chimeric mice examined after 100 postnatal days, the majority of GFP/Mac-1 double-positive cells displayed the morphological features of ramified microglia with fine delicate processes and was distributed diffusely in both gray and white matter. These results suggest that a significant number of donor hematogenous cells are able to infiltrate into the brain parenchyma, repositioning themselves into areas previously occupied by microglia, and to ameliorate lethality.

Animals↗
PubMed2000

Assessing coronary artery disease with thallium-201 rest and technetium-99m-sestamibi stress testing at two centers.

OBJECTIVE: In this study we assessed the specific location(s) of cardiac wall abnormalities in a population of patients referred for coronary artery disease and compared gender differences in the interpretation of nuclear medicine rest/stress results. METHODS: The study group consisted of 846 patients referred to 2 nuclear medicine outpatient cardiology centers for assessment between November 1998 and April 1999. All patients received dual-isotope perfusion 201Tl rest/99mTc-sestamibi stress tests. A retrospective analysis of patient results was performed. RESULTS: In both facilities the largest percentage of defects was identified in the inferior wall (35.5%), followed by the anterior wall (26.5%). Cardiac defects identified in 3 other walls were much lower: lateral wall (14.2%), septal (13.8%), and apical (9.5%). In both outpatient clinics the normalcy rate was much higher for women than men. The normalcy rate in men was 40%, whereas women demonstrated a normalcy rate of 60%. An analysis of treadmill stress versus pharmacologic stress did not illuminate the cause of this difference. CONCLUSION: The most common site of myocardial wall abnormalities occurred in the inferior wall followed by the anterior wall. A large disparity was identified between the results for men compared with those for women. Men had nearly twice the number of defects as women in this study.

Coronary Disease↗
PubMed1999

Efficacy, cycle control, and side effects of low- and lower-dose oral contraceptives: a randomized trial of 20 micrograms and 35 micrograms estrogen preparations.

Estrogen content represents a tradeoff between cycle control and side effects, but few direct comparisons of 20 and 30/35 micrograms preparations are available. To address this issue, we conducted a randomized, open-label multicenter clinical trial comparing Alesse (20 micrograms ethinyl estradiol [EE]), Mircette (20 micrograms EE), and Ortho Tri-Cyclen (35 micrograms EE) among 463 OC starters or switchers. Bloating, breast tenderness, and nausea were approximately 50% more common in women using 35 micrograms EE as compared to 20 micrograms EE preparations. Cycle control was similar in all products, although during the first two cycles among starters; users of Mircette and Ortho Tri-Cyclen (Tri-Cyclen) exhibited better cycle control than Alesse users. Discontinuation and pregnancy rates were not significantly higher in 35 micrograms EE users.

Adolescent↗
PubMed1997

Safety and effectiveness of homemade and reconstituted packet cereal-based oral rehydration solutions: a randomized clinical trial.

OBJECTIVES: Parents may be deterred from obtaining commercial oral rehydration solutions (ORS) for their young children with acute diarrheal disease because of its availability and/or cost, especially if they are poor. We conducted a randomized clinical trial to determine 1) whether low-income parents could safely mix and administer cereal-based ORS (CBORS) both from ingredients commonly found in the home and from a premixed packet; 2) whether these CBORS were as effective in maintaining hydration as commercial glucose-based ORS; and 3) whether CBORS were more effective in reducing severity and duration of illness. METHODS: Children 4 to 36 months of age discharged from emergency departments and health centers with acute diarrheal disease were randomized to receive either homemade CBORS, reconstituted packet CBORS, or Pedialyte. A study nurse saw the child at home each day until the illness resolved, and obtained capillary blood for serum sodium at enrollment and at 24 to 48 hours; a sample of CBORS for sodium concentration; stool for pathogen analysis; and daily fluid intake, stool frequency, and weight. RESULTS: A total of 232 children were enrolled, of whom 203 (88%) completed the study. Two parents (3%) in the homemade CBORS group and one parent (1%) in the packet CBORS group made mixing errors resulting in a high sodium concentration (>100 mEq/L); their children refused the solution and had normal serum sodium values. Mean CBORS sodium concentration for the remainder of the homemade CBORS group was 60 +/- 10 mEq/L, and for the packet CBORS group, 54 +/- 13. Eighteen children (11%) had abnormal serum sodium values at presentation, which returned to normal in all groups in most cases. Three children (4.5%) in the homemade CBORS group, 4 (6%) in the packet CBORS group, and 1 child (1.4%) in the Pedialyte group failed therapy. Children refused to take homemade CBORS and packet CBORS (43% and 32%, respectively) more often than Pedialyte (9%), and those in the CBORS groups tended to take less ORS and total fluids. There were no significant differences among the three groups in incidence of daily vomiting or stooling, duration of diarrhea, or weight gain. CONCLUSIONS: CBORS do not offer a clinically significant advantage over glucose-based ORS. Homemade CBORS represent a treatment option in carefully selected cases, but it is not the safest alternative for regular clinical use.

Acute Disease↗
PubMed1997

A retrospective comparative study of changes in nuclear medicine cardiac stress testing.

UNLABELLED: We evaluated changes in the radiopharmaceuticals and the type of stress testing (either treadmill or pharmacological) used in a variety of nuclear medicine facilities over a 5-yr period, between 1991 and 1996, in Las Vegas, NV. METHODS: Nuclear cardiology patient records at three large hospitals, one large cardiology clinic and the two largest free-standing diagnostic centers in the Las Vegas Valley in 1991 were compared with patient data obtained from the same facilities in 1996. Patient data from each participating site was stratified into treadmill exercise, pharmacological stress testing and type of radiopharmaceutical used. RESULTS: Nuclear medicine cardiology stress testing increased by 55%, from 1991 to 1996. Treadmill exercise testing increased by 14%, while pharmacologically-induced stress testing increased by 202%. All six facilities in the study changed their radiopharmaceutical of choice from thallium in 1991 to a technetium-labeled agent in 1996. CONCLUSION: A large overall growth rate in nuclear medicine stress testing throughout the Las Vegas Valley occurred in hospitals and cardiology clinics between 1991 and 1996. The largest increase was seen in pharmacological stress testing. Over the same period, a decrease in referral base for nuclear stress testing was observed in two outpatient diagnostic centers. All facilities changed from thallium-based to either technetium-based radiopharmaceuticals or dual-isotope methods.

Exercise Test↗
PubMed1996

Effect of adenosine 3',5'-cyclic monophosphate (cAMP) on human non-tumorigenic and tumorigenic parotid acinar cells in culture.

Adenosine 3',5'-cyclic monophosphate (cAMP) regulates growth and/or differentiation of some tumor cells in culture. The effects of cAMP on human parotid acinar cells have never been studied. Results showed that 2HPC8 (non-tumorigenic cells derived from human pleomorphic parotid adenoma) were more sensitive to dibutyryl cAMP, an analog of cAMP, and RO20-1724, an inhibitor of cyclic nucleotide phosphodiesterase, than 2HP1G cells (derived from spontaneous transformation of 2HPC8 cells), suggesting that human parotid adenoma cells maintain a higher degree of cAMP-responsiveness than parotid carcinoma cells. Prostaglandin E1 (PGE1), a stimulator of adenylate cyclase, which increased cAMP levels in 2HPC8 cells, but not in 2HP1G cells, caused a greater degree of growth inhibition in 2HP1G cells than in 2HPC8 cells, suggesting that this effect of PGE1 on tumorigenic cells is not related to cAMP. In the normal parotid and parotid adenoma cell cultures, about 5-10% of cells were small and round, whereas in tumorigenic cell cultures, all cells were small and round. Some indirect evidence suggests that these round cells may be the primary target for transformation. These tumor cells formed cytoplasmic processes of variable length after treatment with cAMP stimulating agents and prostaglandin E1.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

Housing subsidies and pediatric undernutrition.

OBJECTIVE: To test the hypothesis that receipt of housing subsidies by poor families is associated with improved nutritional status of their children. DESIGN: Cross-sectional study. SETTING: Pediatric emergency department of an urban municipal hospital. PATIENTS: Convenience sample of 203 children younger than 3 years and their families who were being seen during one of twenty-seven 24-hour periods. MAIN OUTCOME MEASURES: Anthropometric indicators (z scores of weight for age, weight-for-height, and height-for-age), and the proportion of children with low growth indicator (weight-for-height below the 10th percentile or height-for-age below the fifth percentile, or both, of the reference population). RESULTS: Multivariate analysis controlling for demographics and program participation showed that receipt of housing assistance contributed significantly to z scores for weight-for-age (P = .03) and weight-for-height (P = .04). The risk of a child's having low growth indicators was 21.6% for children whose families were on the waiting list for housing assistance compared with 3.3% for those whose families received subsidies (adjusted odds ratio = 8.2, 95% confidence interval = 2.2 to 30.4, P = .002) CONCLUSION: Receiving a housing subsidy is associated with increased growth in children from low-income families, an effect that is consistent with a protective effect of housing subsidies against childhood undernutrition.

Child Nutrition Disorders↗
PubMed1995

Modern management of acute diarrhea and dehydration in children.

Advances in clinical and laboratory knowledge have led to new concepts in the management of acute infectious diarrhea in children. The major advance has been the development of oral rehydration therapy, which is effective for the treatment of diarrhea of any etiology in patients of any age. Optimal management of acute infectious diarrhea includes the following: (1) rapid rehydration (and maintenance of hydration) using an appropriate glucose-based or cereal-based oral rehydration solution; (2) early refeeding with a mixed diet and no interruption of breast feeding; (3) continuation of lactose-containing foods unless clinical signs of lactose intolerance develop, and (4) a staged laboratory evaluation, with the administration of antimicrobial therapy when indicated.

Acute Disease↗