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Biomedical subjects

H B Carter

Publications and source records attributed to H B Carter.

90 records · Page 5Linked to original sources
PubMed1987

Variables influencing radiation exposure during extracorporeal shock wave lithotripsy. Review of 298 treatments.

Retrospective review of 298 extracorporeal shock wave lithotripsy (ESWL) treatments was undertaken to determine the factors which influence radiation exposure during ESWL. Fluoroscopy time averaged 160 seconds (3-509), and the average number of spot films taken per patient was 26 (5-68). The average stone burden was 19.3 mm (3-64). Average calculated skin surface radiation exposure was 17.8 R per treatment. Radiation exposure increased with increasing stone burden and patient weight. Stones treated in the ureter resulted in a higher average patient radiation exposure than for renal stones (19 R vs 16 R), even though the average size of these ureteral stones (11.3 mm) was significantly less than the mean. However, type of anesthetic (general or regional) used was not a significant factor. Operator training, experience, and familiarity with radiation physics should significantly decrease the amount of imaging time and consequent patient radiation exposure during ESWL.

Anesthesia, Conduction↗
PubMed1987

Newer diagnostic techniques for bladder cancer.

As described in the above paragraphs, efforts in the areas of immunology, cytogenetics, molecular biology, and cytopathology have been applied to the problems urologists face in treating the individual patient with bladder cancer. It is hoped that continued investigations in these disciplines will not only lead to earlier diagnosis of bladder cancer and better prediction of tumor behavior but will further our understanding of the molecular basis of oncogenesis.

Humans↗
PubMed1986

Fine needle aspiration of the abnormal prostate: a cytohistological correlation.

Cytological diagnosis by fine needle aspiration of the prostate was compared to histological diagnosis by either perineal needle biopsy or transurethral prostatic resection in 110 patients suspected to have prostatic cancer by rectal examination. Of the 94 prostatic aspirations that could be given a definite cytological diagnosis there was histological correlation in 85 (90.4 per cent). The false negative rate was 2.7 per cent for fine needle aspiration and 5.3 per cent for perineal needle biopsy. Inadequate cytological samples occurred mainly at the beginning of the study. There was a 69 per cent correlation in 36 cases in which cytological grading was compared to histological grading. Our results indicate that fine needle aspiration is an easily performed, diagnostically reliable outpatient procedure with minimal complications that also can be used for grading purposes.

Biopsy, Needle↗
PubMed1985

Lethality in mice and rats exposed to 2450 MHz circularly polarized microwaves as a function of exposure duration and environmental factors.

Adult male CD-1 mice and CD rats were used to determine LD50/24 h lethality rates from exposure to 2450-MHz circularly polarized microwaves. Groups of 16 mice or six rats were exposed in each of 32 combinations of nominal power density (10, 25, 50 or 75 mW cm-2), exposure duration (1 or 4 h), and environmental temperature (20 or 30 degrees C) and relative humidity (35 or 80%). An analysis of variance probit model was used to determine the influence each variable had on the probability of death. Significant factors in lethality were nominal power density, exposure duration and environmental temperature, but not environmental relative humidity. The estimated power density (mW cm-2) required to kill 50% of the animals in 24 h is halved when the environmental temperature is increased from 20 to 30 degrees C. Similarly, only 20-25% of the power density is required when the exposure duration is increased from 1 to 4 h. The use of nominal power density as a predictor of the probability of death was more efficient than specific absorption rate estimated experimentally by twin-well calorimetry. The exposure of one mouse at a time, instead of 16, did not alter the predicted death rate.

Animals↗
PubMed1985

Description and implications for analysis of brain growth in suckling mice.

The growth pattern of the brains of normal CD-1 mice was studied from day 1 through day 21 after birth. The main purpose of the study was to decide on suitable methods of statistical analysis of these kinds of data including whether to analyze brain weight or the brain-to-body weight ratio. A secondary purpose, which aided the main purpose, was to find functions that describe the relationships between growth parameters. Linear-linear segmented polynomials were found to describe well the relationships between brain weight and body weight, brain weight and age, brain-to-body weight ratio and body weight and brain-to-body weight ratio and age. The analyses indicated that brain weight alone is the preferred variable to analyze. Regression analysis of brain weight with sex and up to the first three powers of body weight and age as independent variables would be a suitable method of analysis. Litter size per se had no effect on brain weight.

Aging↗
PubMed1985

The reliability of the results of ultrasound detection of fluid collections in the early postceliotomy period.

The results of this prospective clinical study have demonstrated a low rate of false-positive abdominal sonographic findings in patients undergoing routine studies the seventh day after abdominal surgical procedures. It is concluded that any intraperitoneal fluid collection detected by ultrasound examination in a patient postoperatively demonstrating signs and symptoms of abdominal sepsis (fever, leukocytosis, pain, tenderness, persistent ileus, excessive drainage, wound changes and so on), should be considered as the source, as abdominal fluid collections do not persist as a "normal" part of the healing process one week after extensive biliary tract or colonic operations. Sonography is a highly specific procedure for the detection of abdominal abscesses after the seventh postoperative day. The type of procedure, type of incision, type of closure, presence of drains, history of prior intraperitoneal surgical procedures and operative blood loss did not affect the accuracy of the test. Postoperative ultrasonography is a specific, sensitive and accurate test and is widely applicable to almost all groups of patients.

Ascitic Fluid↗
PubMed1984

Growth and development of mice offspring after irradiation in utero with 2,450-MHz microwaves.

Mice offspring irradiated in utero with 2,450-MHz radio-frequency (RF) radiation at 0 or 28 mW/cm2 (whole-body averaged specific absorption rate = 0 or 16.5 W/kg) for 100 minutes daily on days 6 through 17 of gestation were evaluated for maturation and development on days 1, 5, 10, 12, 15, and 17 of age. The tests used to determine differences in developmental age in the two treatment groups were body weight, urine concentrating ability, brain weight, tolerance to ouabain, and bone lengths. Fifteen sham-irradiated and 26 RF-irradiated litters, normalized to eight pups/litter, were used in this study. Mean body weight of the microwave-irradiated offspring were significantly (p = .0003) decreased only on day 1 of age. Brain weight on days 10, 12, and 17 were significantly lower in microwave-irradiated pups (p = .01). There were no significant differences in the two groups in urine concentrating ability on day 5, ouabain tolerance on day 15, or bone length on days 5, 10, 12, and 17. It is concluded that there is a persistent delay in postnatal development of the brain after RF irradiation with 16.5 W/kg during gestation.

Animals↗
PubMed1984

Decreased body weight in fetal rats after irradiation with 2450-MHz (CW) microwaves.

Female Sprague-Dawley (CD) rats were exposed to 2450-MHz (CW) microwave radiation at incident power densities of 0 or 40 mW/cm2 (SAR = 6.0 W/kg) for 100 min daily on the sixth through 15th day of gestation. One-time exposure to the same conditions increased average colonic temperatures 2 degrees C at the end of irradiation in pregnant rats of similar size. There were 23 sham-irradiated and 24 microwave-irradiated females. When these groups were compared on the 21st day of gestation, no significant differences were found in pregnancy rates; in the numbers of live, dead or total fetuses; nor in the incidences of external, visceral or skeletal anomalies or variations. However, mean fetal body weight was significantly (p = 0.0008) lower after microwave irradiation and was 9% less than that of sham-irradiated litters. Sternal ossification was also significantly delayed in the microwave-irradiated fetuses (p = 0.007). It is concluded that even though a change in the malformation rate is not effected in rats, a fetotoxic effect does occur due to microwave-exposure conditions which raise maternal rectal temperatures to approx. 40 degrees C and produce a specific absorption rate (SAR) greater than or equal to 6 W/kg in the dam.

Animals↗
PubMed1982

Reduced weight in mice offspring after in utero exposure to 2450-MHz (CW) microwaves.

Time-bred CD-1 mice (100) were sham-irradiated or irradiated with 2450-MHz (CW) microwaves at 28 mW/cm2 for 100 minutes daily from the 6th through 17th day of gestation. The offspring were examined either as fetuses after hysterotomy on the 18th day of gestation or as naturally born neonates on the 1st and 7th day of age. Fetuses of half of the dams were examined on the 18th day of gestation. The incidence of pregnancy and the numbers of live, dead, resorbed, and total fetuses were similar in both groups. The mean weight was significantly lower (10%) in live microwave-irradiated fetuses, and ossification of sternal centers was significantly delayed. In the offspring that were born naturally, the mean weight of microwave-irradiated 7-day-old suckling mice was significantly lower (10%) than that of the sham-irradiated group. Survival rates of neonates in these two groups were not different. These data demonstrate that the decreased fetal weight seen in microwave-irradiated mice is retained at least 7 days after birth. Evidence from other published studies is presented to show that the retarded growth is persistent and might be interpreted as permanent stunting.

Animals↗
PubMed1982

Observations of Syrian hamster fetuses after exposure to 2450-MHz microwaves.

The teratogenic potential of microwaves was examined in a rodent species, the Syrian hamster. Exposure of hamsters to 2450-MHz CW microwaves at a power density of 20 mW/cm2 (estimated SAR = 6 mW/g) for 100 minutes daily on days 6-14 of gestation caused no significant change in fetal survival, body weight, skeletal maturity, or incidence of terata. Thirty mW/cm2 (estimated SAR = 9 mW/g) caused significantly increased fetal resorptions, decreased fetal body weight, and decreased skeletal maturity. Rectal temperatures of pregnant hamsters after exposure to 20 mW/cm2 were slightly increased (0.4 degrees C) over those of sham-irradiated dams; 30 mW/cm2 caused maternal rectal temperatures to be increased 1.6 degrees C over sham-irradiated dams' temperatures. It appears that the hamster fetus may be more susceptible to microwave radiation than the mouse.

Abnormalities, Radiation-Induced↗
PubMed1981

Observations of rat fetuses after irradiation with 2450-MHz (CW) microwaves.

Female Sprague-Dawley (CD) rats were exposed to 2450-MHz (CW) microwave radiation at incident power densities of 0 or 28 mW/cm2 for 100 min daily on the 6th through 15th day of gestation. The whole-body specific absorption rate at 28 mW/cm2 is estimated to be 4.2 W/kg. These exposure conditions raised rats' average colonic temperatures to 40.3 degrees C at the end of irradiation. There were 67 sham-irradiated and 70 microwave-irradiated females. When these groups were compared, no significant differences were found in pregnancy rates; in the numbers of live, dead, or total fetuses; in the incidences of external, visceral, or skeletal anomalies or variations; or in the body weight of live fetuses. It is concluded that these conditions do not have an effect on the gross structure of the fetal rat when applied repetitively during post-implantation pregnancy. It is also strongly suspected that this lack of an effect may hold true at any exposure level less than that which will kill a significant number of the dams by hyperthermia (colonic temperature greater than 40 degrees C).

Animals↗
PubMed1980

Tests of mutagenesis and reproduction in male rats exposed to 2,450-MHz (CW) microwaves.

Tests of mutagenesis and reproduction were conducted in male rats which were irradiated by 2,450-MHz, continuous-wave (CW) microwaves, 4 hr/day from day 6 of gestation to 90 days of age at 5 mW/cm2; or 5 hr/day for five days beginning on the 90th day of age at 10 mW/cm2; or 4 hr/day, 5 days/wk for four weeks, beginning on the 90th day of age. During selected weekly periods after treatment, the rats were bred to pairs of untreated, normal female rats that were examined in late pregnancy by means of dominant lethal assay. The reproductive efficiency of these males, as reflected in their breeding, was also examined for changes relating to their microwave experience. No significant evidence of germ-cell mutagenesis was detected when data of microwave-exposed males were compared with those of sham-exposed males, even though there were significant increases in rectal and intra-testicular temperatures at a power density of 28 mW/cm2. Temporary sterility, as indexed by fewer pregnancies, was seen at the highest power density.

Animals↗
PubMed1978

Changes in macromolecular synthesis and nucleoside triphosphate levels during glycerol-induced growth stasis of Escherichia coli.

Experiments were performed to determine how glycerol affects macromolecular syntheses and nucleoside triphosphate levels in a strain of Escherichia coli that lacks a functional sn-glycerol-3-phosphate dehydrogenase. The addition of glycerol to cultures of this strain, Lin 8, growing on a gluconeogenic carbon source causes immediate growth stasis (N. R. Cozzarelli, J. P. Koch, S. Hayashi, and E. C. C. Lin, J. Bacteriol. 90:1325-1329, 1965). Immediately after the addition of glycerol to cultures of Lin 8, the syntheses of DNA, RNA, and protein are completely inhibited. Phospholipid synthesis is not inhibited as severely by glycerol. The addition of glycerol to strain Lin 8 also results in a rapid decrease in its nucleoside triphosphate levels. The total intracellular concentration of ATP in strain Lin 8 was reduced by 85% within 30 s after the addition of glycerol. These results suggest that the glycerol-induced inhibition of growth and macromolecular syntheses may be a secondary consequence of the decreased energy supply in this strain. In addition, studies also suggest that phospholipid synthesis can continue (albeit at a reduced rate) under conditions of severe energy limitation.

Adenosine Triphosphate↗
PubMedDate not supplied

Mixed-effects regression models for studying the natural history of prostate disease.

Although prostate cancer and benign prostatic hyperplasia are major health problems in U.S. men, little is known about the early stages of the natural history of prostate disease. A molecular biomarker called prostate specific antigen (PSA), together with a unique longitudinal bank of frozen serum, now allows a historic prospective study of changes in PSA levels for decades prior to the diagnosis of prostate disease. Linear mixed-effects regression models were used to test whether rates of change in PSA were different in men with and without prostate disease. In addition, since the prostate cancer cases developed their tumours at different (and unknown) times during their periods of follow-up, a piece-wise non-linear mixed-effects regression model was used to estimate the time when rapid increases in PSA were first observable beyond the background level of PSA change. These methods have a wide range of applications in biomedical research utilizing repeated measures data such as pharmacokinetic studies, crossover trials, growth and development studies, aging studies, and disease detection.

Aged↗
PubMedDate not supplied

Prostatic growth rate determined from MRI data: age-related longitudinal changes.

Men with prostatic enlargement are at highest risk of developing symptomatic lower urinary tract symptoms (LUTS) and related outcomes, such as acute urinary retention. The study of prostatic growth rate can identify the age range at which prostate growth peaks. Evaluation of the natural course of prostate growth requires repeated intraindividual volume measurements at time intervals sufficient to document growth. Our objective was to examine age-stratified prostate growth rates from men taking part in a longitudinal study of aging using magnetic resonance imaging (MRI) of the prostate. Sixty-four men (ages 30-71 years) enrolled in the Baltimore Longitudinal Study of Aging (BLSA) who had T2 pelvic MRIs taken approximately every 2 years were studied. Men were age stratified into four groups: <45, 45-55, 56-65, and >65 years old. Whole prostate and central gland (anatomically referred to as the transition zone) volumes were determined from the MRI images by a semi-automated image analysis program. Peripheral gland volumes were calculated as the difference between whole prostate and central gland volumes. Growth rates (cc per year) were calculated as change in volume divided by the time interval. On the basis of measurements from the T2 images (n = 128), we observed a linear trend between prostate volume and age. The overall prostate growth rate was 2.36 +/- 3.52 cc per year. Age-stratified growth rates revealed that prostate growth increased with age, peaked at 4.15 +/- 4.98 cc/year for the 56-65-year-old age group and then declined rapidly for the older-aged men. The central gland growth rates followed a trend similar to total prostate volume. These data suggest that there is an age-related increase in prostate growth rate that peaks in men ages 56-65 and then declines. Identification of this trend in prostate growth may aid physicians in targeting men for early diagnosis of LUTS and for possible early intervention. Future studies with a larger sample size are necessary to substantiate these findings.

Adolescent↗
PubMedDate not supplied

Longitudinal evaluation of prostate-specific antigen levels in men with and without prostate disease.

OBJECTIVE: To evaluate longitudinal changes in prostate-specific antigen (PSA) levels in men with and without prostate disease. DESIGN: Case-control study of men with and without prostate disease who were participants in a prospective aging study. SETTING: Gerontology Research Center of the National Institute on Aging; the Baltimore (Md) Longitudinal Study of Aging. PATIENTS: Sixteen men with no prostate disease (control group), 20 men with a histologic diagnosis of benign prostatic hyperplasia (BPH), and 18 men with a histologic diagnosis of prostate cancer. OUTCOME MEASURES: Multiple PSA and androgen determinations on serum samples obtained from 7 to 25 years prior to histologic diagnosis or exclusion of prostate disease. RESULTS: Changes in androgen levels with age did not differ between groups. Control subjects did not show a significant change in PSA levels with age. There was a significant difference in the age-adjusted rate of change in PSA levels between groups (prostate cancer greater than BPH greater than control; P less than .01). At 5 years before diagnosis when PSA levels did not differ between subjects with BPH and prostate cancer, rate of change in PSA levels (0.75 micrograms/L per year) was significantly greater in subjects with prostate cancer compared with control subjects and subjects with BPH. Also, rate of change in PSA levels distinguished subjects with prostate cancer from subjects with BPH and control subjects with a specificity of 90% and 100%, respectively. CONCLUSIONS: The most significant factor affecting serum PSA levels with age is the development of prostate disease. Rate of change in PSA levels may be a sensitive and specific early clinical marker for the development of prostate cancer.

Aged↗