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Biomedical subjects

D Fleming

Publications and source records attributed to D Fleming.

At least 73 records · Page 4Linked to original sources
PubMed1986

Estimation of acoustic attenuation in liver using one megabyte of data and the zero-crossings technique.

Statistical fluctuations due to scatter-induced frequency variations in reflected acoustic pulses are a major problem when estimating acoustic attenuation. Disagreement exists in the ultrasound community as to how much data is sufficient to overcome these statistical fluctuations. The range of attenuation values for normal livers and a tissue equivalent phantom, using 1 megabyte of data per liver and the zero-crossings technique, was investigated. The significance of statistical fluctuations and their effects on attenuation are discussed.

Acoustics↗
PubMed1984

The structure of the vomeronasal organ and nasopalatine ducts in Aotus trivirgatus and some other primate species.

A vomeronasal organ and patent nasopalatine ducts were found in adult specimens of Aotus trivirgatus, Arctocebus calabarensis, Ateles geoffroyi and Saguinus fuscicollis. The vomeronasal complex appeared to be functional except in Ateles. However, the relative size of the organ in the Platyrrhini is much reduced compared to that in prosimians. The possible role of the organ in mediating neuroendocrine processes in primates is discussed.

Animals↗
PubMed1981

The declining length of hospitalization for tubal sterilization.

We analyzed factors affecting the length of hospital stay for tubal sterilization in 1970 and 1975, using data from the National Center for Health Statistic's Hospital Discharge Survey. The average hospital stay for tubal sterilization declined from 6.5 nights in 1970 to 4.0 nights in 1975. Pregnancy status, region of residence, and race were important determinants of the length of hospital stay. One technological innovation, the use of the laparoscope for tubal sterilization, accounted for 39% of the total length-of-stay reduction from 1970 to 1975. General changes in medical care from 1970 to 1975, combined with the introduction of laparoscopy, averted 1,363,000 nights of hospitalization for tubal sterilization in 1975. Conservatively, this resulted in a savings of more than $200 million. About $80 million of this savings was directly attributable to laparoscopy. Even greater savings could have been achieved if sterilization techniques requiring shorter hospital stays had been more widely used.

Black People↗
PubMed1980

Plasma concentrations of oestradiol-17 beta, oestrone, progesterone and testosterone during the ovarian cycle of the owl monkey (Aotus trivirgatus).

Oesterone, oestradiol-17 beta, progesterone and testosterone were measured by radioimmunoassay in daily plasma samples throughout the ovarian cycle in 4 female owl monkeys. Clearly defined peaks of oestradiol-17 beta occurred at intervals of 15.5 +/- 0.56 days and confirmed the length of the cycle reported previously. Progesterone rose on the day on the day of the oestradiol-17 beta to reach a maximum 4--6 days later, thereafter decreasing gradually to low levels before the onset of the next cycle. On the basis of these data the follicular and luteal phases were estimated to be 6 and 10 days respectively. Osterone and testosterone peaks preceded that of progesterone by 24 and remained elevated throughout the luteal phase. Plasma concentrations of all steroids were markedly higher than for other primate species. Vaginal cytology was considered unsuitable as an indicator of the stage of the ovarian cycle.

Animals↗
PubMed1980

Demographic trends of tubal sterilization in the United States 1970-75.

An estimated 2,300,000 women in the United States underwent tubal sterilizations in 1970-1975. During this period the rate of tubal sterilizations per 1,000 women 15-44 years of age rose from 4.7 to 11.7. We studied the influence on sterilization trends of four demographic variables: age, region of residence, race, and marital status. Women 25-34 years of age were twice as likely to be sterilized as older or younger women. Rates were about 40 per cent lower in the West than in the rest of the country. In 1970 rates for non-white women were double those for Whites. Rates for Whites rose faster than those for non-Whites, however, and by 1975 the rates were similar for the 2 races. Non-Whites still tended to be sterilized about one year younger than Whites, and marked regional differences existed in the race-specific rate trends. Rates rose more sharply for previously married women than for currently married women; by 1975 rates for these two groups were similar. Never married women had rates about 1/7 of those of currently married and previously married women. Among the never married, tubal sterilization rates for non-Whites were nine times higher than those for Whites.

Adolescent↗
PubMed1979

Cyclic changes in the circulating and urinary levels of ovarian steroids in the adult female owl monkey (Aotus trivirgatus).

Circulating levels of oestrone and progesterone were measured by radioimmunoassays in plasma samles from 5 female owl monkeys on 60 consecutive days. Both steroids exhibited cyclic fluctuations and based on nadir to nadir intervals the ovarian cycle was estimated to be 15.92 +/- 0.26 days. Levels of oestrone and pregnanediol-3 alpha-glucuronide were also measured in daily urine samples. The fluctuations of urinary steroids reflected those observed in plasma. Ketamine sedation had no effect on the length of the cycle. Peak values of plasma progesterone and oestrone were 250.48 +/- 11.37 and 3.59 +/- 0.066 ng/ml respectively. There was no clear hormonal distinction between the follicular and luteal phase of the cycle in these owl monkeys.

Animals↗
PubMed1978

Aging in the rhesus monkey: debilitating effects on short-term memory.

The performance of aged rhesus monkeys (18 years and older) was compared to that of young control monkeys (three to five years old) in three experiments designed to define and evaluate the presumed short-term memory impairment associated with aging. An automated, indirect delayed-response procedure was used with special emphasis directed toward controlling or eliminating potentially confounding variables such as attention, motivation, learning disabilities, etc. It was shown that the aged monkeys do suffer from a profound a specific impairment in short-term memory (STM), performing normally on the shortest dealy interval and showing progressively greater impairment as the retention interval was increased. A subsequent study varied deprivation level and demonstrated that it is unlikely that differences in motivation could account for the age-related STM deficits observed on the delayed-response task. Further studies indicated that alterations in stimulus availability did not differentially affect the performance of the two age groups to any measurable extent, suggesting that differences in stimulus processing abilities are neigher necessary nor sufficient conditions for the deficit found in the first experiment. These results suggest that the delayed-response deficity in old monkeys is directly related to age-associated changes in those areas of the nervous system which are important for the expression of short-term memory.

Aging↗
PubMed1977

Digital K-edge subtraction radiography.

K-edge subtraction images have been produced using a digital video image processor. Images formed by three filtered x-ray beams are detected by an image intensifier-Plumbicon system, digitilized, and combined in real time to produce bone- and tissue-free K-edge subtraction images of iodinated structures. Preliminary studies of rhesus monkey cranial, spinal, and abdominal structures are compared with those of conventional radiography.

Animals↗