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Biomedical subjects

A Hardy

Publications and source records attributed to A Hardy.

At least 37 records · Page 2Linked to original sources
PubMed1995

Gene expression, polarising activity and skeletal patterning in reaggregated hind limb mesenchyme.

The developing chick limb has two major signalling centres; the apical ectodermal ridge maintains expression of several important genes and outgrowth of the limb, and the polarising region specifies the pattern of skeletal elements along the anteroposterior axis. We have used reaggregated leg grafts (mesenchyme dissociated into single cells, placed in an ectodermal jacket and grafted to a host) to study patterning in a system where the developmental axes are severely disrupted. Reaggregates from different regions of leg mesenchyme developed correspondingly different digits, giving a system in which skeletal phenotype could be compared with the expression of genes thought to be important in patterning. We found that posterior third and whole leg reaggregates gave rise to different digits, yet expressed the same combination of HoxD, Bmp-2 and shh genes throughout their development. Anterior thirds initially only express the 3' end of the HoxD cluster but activate the more 5' members of the cluster sequentially over a period of 48 hours, a period during which Bmp-2 is activated but no shh or Fgf-4 expression could be detected. Our results suggest that there are two independent mechanisms for activating the HoxD complex, one polarising region-dependent and one independent, and that shh expression may not be necessary to maintain outgrowth and patterning once a ridge has been established.

Animals↗
PubMed1995

Health habits of recovering alcoholics.

Heavy drinkers and alcoholics are known to have generally poor health habits in terms of cigarette smoking, seat belt use, diet, and preventive health practices. Little is known, however, about health habits of recovering alcoholics. We analyzed national survey data to describe the health habits of recovering alcoholics compared with heavy drinkers (four or more drinks per day). Recovering alcoholics had a significantly elevated odds of using seat belts regularly and reporting preventive health practices that are known to reduce the risk of cardiovascular disease. In addition, recovering alcoholics were at significantly decreased odds of being cigarette smokers. Although the cross-sectional data have limitations, they indicate there may be more health benefits in recovery from alcoholism than abstinence alone.

Adolescent↗
PubMed1994

Sequence and regulation of European eel prolactin mRNA.

cDNA clones encoding the European eel (Anguilla anguilla L.) prolactin were isolated from a pituitary cDNA library constructed in gamma gt10, using a rainbow trout Prl cDNA fragment as a probe. Four different inserts were subcloned into the pGEM 3Z plasmid after PCR amplification. The 1082 bp-long nucleotide sequence revealed an open reading frame of 627 bp encoding a 24 amino acid-long signal peptide followed by a 185 amino acid-long mature protein. Comparison studies showed 60-70% homology with other known teleost fish prolactins and 30-45% with non-teleost fish, amphibian, reptilian, avian and mammalian prolactins. In situ hybridization studies using labelled prolactin RNA probe showed a strong signal in the rostral pars distalis of the pituitary gland. We next examined the physiological regulation of this prolactin synthesis in vivo using Northern blot analysis and prolactin cDNA probe labelled by random priming. The pituitary prolactin mRNA level was markedly decreased 3 weeks after transfer of eels from freshwater to sea water. Implants of thyroid hormones left for up to three weeks were ineffective on prolactin mRNA. Estradiol administered as implant, alone or in combination with 500 micrograms testosterone, was also unable to significantly alter the pituitary mRNA level for prolactin in the freshwater silver eels whatever the dose used (20-500 micrograms) and whatever the duration of treatment (from 4 days to 10 weeks).

Amino Acid Sequence↗
PubMed1994

'Death is the cure of all diseases': using the General Register Office cause of death statistics for 1837-1920.

The series of cause of death statistics for England and Wales published by the General Register Office between 1837 and 1920 are a fundamental source for historians studying death and disease in this period. Attention was first drawn to the historical importance of this source, and to its principal shortcomings, by Bill Luckin in 1980. Research by a number of scholars in recent years on mortality and morbidity in the nineteenth century has uncovered further problems, which are outlined in this essay under two heads: general problems, and problems relating to specific cause of death categories.

Cause of Death↗
PubMed1993

Doppler-derived aortic maximal acceleration. A reliable index of left ventricular systolic function.

We compared maximal acceleration of aortic blood flow (aortic Amax), calculated from maximal aortic velocity obtained with a conventional echo-Doppler machine with the invasive inotropic index left ventricular end-systolic pressure/left ventricular end-systolic volume (LVESP/LVESV) ratio and left ventricular ejection fraction (LVEF). Continuous wave (CW) and pulsed wave (PW) Doppler aortic blood flows were recorded from the apical view in 16 patients (age, 62.3 +/- 6.4 years) within 24 h of left-sided catheterization. The theoretical exponential relationship between LVEF and LVESP/LVESV was confirmed in our study population (r = 0.92; p < 0.0001). The relationship between aortic Amax determined either by CW or PW and LVESP/LVESV was linear (r = 0.92 and 0.93, respectively, p < 0.001), whereas the relationship between aortic Amax and angiographic LVEF was exponential (PW: r = 84; CW: r = 0.85; both p < 0.001). We conclude that (1) aortic Amax, derived from maximal velocity obtained with a conventional machine, can be used as an index of left ventricular systolic function, and (2) PW as well as CW Doppler signals can be used for this calculation.

Aged↗
PubMed1992

Active dosimetric measurements on shuttle flights.

A tissue-equivalent proportional counter spectrometer capable of measuring the absorbed dose and dose distribution as a function of linear energy transfer (LET) and time, for all penetrating radiation in space, is described. This instrument weighs about 0.7 kg and was flown on the STS-31 (28.5 degrees x 620 km) flight of the Space Shuttle, 24-29 April 1990. The measured total dose is in excellent agreement with the calculations based on the AP8MAX model of the trapped radiation belt protons. The observed LET frequency distribution is also in excellent agreement with calculations based on this model. Active instruments can provide more detailed dosimetry for crew risk assessment than the thermoluminescent detectors or a plastic track detector system.

Cosmic Radiation↗