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Biomedical subjects

R W Hardy

Publications and source records attributed to R W Hardy.

At least 91 records · Page 5Linked to original sources
PubMed1982

Central cord syndrome as a delayed postoperative complication of decompressive laminectomy.

We report five cases of a central cord syndrome that appeared as a delayed surgical complication several days after decompressive laminectomy with the patient in the sitting position. Some episode of abnormal positioning of the neck or hypotension seems to have triggered the central cord syndrome. The patients improved slowly, but did not return to their immediate postoperative status. This complication probably can be avoided with careful mobilization after operation, with the avoidance of hypotension, and with the use of a firm collar during the first few postoperative days.

Aged↗
PubMed1981

Analysis of spermatogenesis in Drosophila melanogaster bearing deletions for Y-chromosome fertility genes.

The effects of spermatogenesis of a series of continguous non-overlapping Y-chromosome deficiencies were examined using both the light and electron microscope. The deficiencies were constructed by combining elements of different X-Y translocations; they subdivide the Y into seven segments, six of which are required for male fertility (four in the long arm and two in the short arm). Spermatogenesis was examined from the primary spermatocyte through to the formation of mature sperm and the earliest departures from normal development identified. Two deficiencies result in the absence of the same structure from the axoneme of the sperm tail--the dynein-containing outer arm extending from the A subtubule of the peripheral doublet; they also result in the absence from primary spermatocyte nuclei of aggregates of tubuli in one case and reticular material in the other. A third deficiency causes the appearance in the primary spermatocyte of the crystals characteristic of X0 males and the irregular distribution during meiosis of nuclear and cytoplasmic elements to the spermatids. The fourth deficiency results in the misalignment of the developing axoneme with the mitochondrial derivatives and is first detectable in the onion nebenkern stage of the spermatid. Finally for two deficiencies the first abnormalities detected were during later stages and comprise a syndrome found in most of the steriles. We attribute this phenotype to the indirect effects of earlier lesions.

Animals↗
PubMed1980

Human fibroblast interferon: amino acid analysis and amino terminal amino acid sequence.

The purification of human fibroblast interferon has been simplified to a two-step procedure consisting of affinity chromatography on Blue Sepharose and sodium dodecyl sulfate polyacrlamide gel electrophoresis. A preliminary amino acid composition and the sequence of the 13 amino-terminal residues of homogeneous interferon prepared by this method is reported.

Amino Acid Sequence↗
PubMed1980

Surgical treatment of compressive cervical band.

Compression of the lower portion of the brachial plexus by a cervical band continuous with the scalenus medius is a rare but well-defined cause of arm pain. The syndrome should be suspected in a patient who presents with chronic arm pain and thenar atrophy. Cervical ribs or prominent C-7 transverse processes will be present on an anteroposterior roentgenogram of the cervical spine, and the diagnosis is confirmed by characteristic electromyographic findings. The syndrome should be differentiated from other causes of chronic arm pain, such as herniated cervical disc, syringomyelia, spinal cord tumor, or carpal tunnel syndrome. The condition is readily treated by surgical division of the compressive band, approached through a supraclavicular incision.

Adult↗
PubMed1980

The combined multidisciplinary approach to invasive basal cell tumors of the scalp.

Deeply invading tumors of the scalp present numerous extirpative and reconstructive problems requiring the combined expertise and skills of both medical and surgical disciplines. We have employed a combined multidisciplinary approach to recurrent tumors of the scalp and calvarium. Intraoperatively, a fresh-tissue mapping modification of Mohs' histographic surgical technique is performed on the entire surgical specimen. This allows for total microscopic margin control of a recurrent basal cell carcinoma during a single surgical procedure. The resulting defect is immediately reconstructed by myocutaneous free flap transfer using microvascular techniques.

Adult↗
PubMed1978

The opportunity for and significance of alteration of ribulose 1,5-bisphosphate carboxylase activities in crop production.

Increased population and the dietary changes accompanying increased affluence are creating a need for a suggested doubling of world cereal grain production (a 3% per year compounding rate) and quadrupling of grain legume production (a 6% per year compounding rate) during this quarter century (1). CO2 enrichment of field-grown crops has demonstrated the possibility of enhancing RuBP carboxylase activity to achieve improved crop production; it increases the production of grain legumes by 50 to 100% and that of cereal grains, for which the studies are less complete, by perhaps 10 to 50%. Results of O2 alteration of growth-room legumes and cereal grains are consistent with the results of CO2 enrichment except for a second role of O2 in assimilate partitioning. It may be necessary to include other components of the system, e.g., additional soil fertility, especially for non-N2-fixing plants, to enable an improved RuBP carboxylase to increase production. No practical method--chemical, genetic, or physical--of improving RuBP carboxylase activity has been reported.

Agriculture↗
PubMed1978

Dural arterio-venous malformations involving the cavernous sinus: a case report.

A case of dural arteriovenous malformation involving the cavernous sinus is reported. The patient was successfully treated with selective embolisation of the fistula. These patients constitute a distinct neuro-ophthalmological syndrome which may be very difficult to diagnose clinically because of the subtle signs and symptoms they present with. Angiography is necessary to make diagnosis and to differentiate these patients from those with the more common carotidcavernous fistulae.

Adult↗
PubMed1976

Adaptation of Nitrogen Fixation by Intact Soybean Nodules to Altered Rhizosphere pO(2).

The N(2)-fixing legume nodule requires O(2) for ATP production; however, the O(2) sensitivity of nitrogenase dictates a requirement for a low pO(2) inside the nodule. The effects of long term exposures to various pO(2)s on N(2)[C(2)H(2)] fixation were evaluated with intact soybean (Glycine max [L.] Merr., var. Wye) plants. Continuous exposure of their rhizosphere to a pO(2) of 0.06 atmospheres initially reduced nitrogenase activity by 37 to 45% with restoration of original activity in 4 to 24 hours and with no further change in tests up to 95 hours; continuous exposure to 0.02 atmosphere of O(2) initially reduced nitrogenase activity 72%, with only partial recovery by 95 hours. Similar exposures to a pO(2) of 0.32 atmospheres had little effect on N(2)[C(2)H(2)] fixation; a pO(2) of 0.89 atmospheres initially reduced nitrogenase activity by 98% with restoration to only 14 to 24% of that of the ambient O(2) controls by 95 hours. Re-exposure to ambient pO(2) of plants adapted to nonambient pO(2)s reduced N(2)[C(2)H(2)] fixation to similar magnitudes as the reductions which occurred upon initial exposure to variant pO(2) conditions, and a time period was required to readapt to ambient O(2). It is concluded that the N(2)[C(2)H(2)]-fixing system of intact soybean plants is able to adapt to a wide range of external pO(2)s as probably occur in soil. We postulate that this occurs through an undefined mechanism which enables the nodule to maintain an internal pO(2) optimal for nitrogenase activity.

Journal Article↗
PubMed1976

Alexia without agraphia.

This typical case of alexia without agraphia, caused by an astrocytoma, is the first recorded case in the literature of alexia without agraphia with a right homonymous hemianopia caused by a tumor. This case differs from previously reported cases of the syndrome by its fluctuating clinical course and its slow progression. All but one of previously reported cases had been of vascular or surgical etiology. This course and the associated radiographic findings should differentiate the neoplastic from the vascular etiology of this most fascinating syndrome.

Astrocytoma↗
PubMed1975

The influence of chromosome content on the size and shape of sperm heads in Drosophila melanogaster and the demonstration of chromosome loss during spermiogenesis.

The volumes of sperm heads were estimated from three-dimensional reconstructions of serially sectioned bundles of nearly mature spermatid nuclei. Cysts from males in which all sperm are expected to have comparable amounts of chromatin (X/Y and 1n(3LR)/+) show unimodal frequency distributions of nuclear volumes, whereas cysts from males in which meiotic segregation is expected to deliver unequal amounts of chromatin material to spermatid nuclei show two (XY/O and XY/Y) or more (T(2;3)/+ ANd C(2L);C(2R)) modes. The mean volumes of the subpopulations in these cases are related in the same proportions as the metaphase lengths of their chromosomal complements. Thus the volumes of sperm nuclei are proportional to their DNA content. Sperm head shape, on the other hand, does not appear to be very sensitive to chromosomal constitution, as heads of different size do not vary greatly in shape.----The numbers of sperm heads in the various size classes in a cyst depart from mendelian expectations; these departures are caused by the elimination, during individualization, of chromosomes contained within micronuclei that are formed in spermatids at the end of the second meiotic division. The effect of this chromosome loss is to increase the proportion of nullosomic gametes in the sperm pool.----The relative frequencies of XY-bearing and nullo-X, nullo-Y sperm in XY/O males were estimated from the volume measurements. Taking this estimate as a measure of the fertilizing population, it is possible to infer from the change in sex ratio over time following insemination, that XY-bearing sperm have an advantage of 1.5 over nullo-X, nullo-Y sperm in leaving the seminal receptacle of the female for fertilization of ova.

Animals↗
PubMed1975

Reproductive Growth and Dry Matter Production of Glycine max (L.) Merr. in Response to Oxygen Concentration.

Reproductive as well as vegetative parameters of mature soybean (Glycine max [L.] Merr. cv. Wye) plants grown in chambers in which the aerial portion was exposed to altered pO(2) during all or part of the growth cycle were measured. Oxygen concentration was found to be a key factor controlling all phases of reproductive development. Exposure to 5% O(2) from early seedling stage to senescence increased leaf, stem, and root dry weights and reduced seed yields when compared to 21% O(2); exposure to low O(2) during the vegetative growth stage from early seedling to mid-flowering arrested pod but not seed development; exposure from mid-flowering to mid-pod filling almost completely arrested seed but not pod development; exposure from mid-pod filling to senescence arrested seed development at the mid-filling stage.Exposures to 5% O(2) initiated at mid-flowering for 1, 2, 3, 5, 10, and 15 days had no effect on seed development when the exposure was up to 3 days and produced almost total arrest when the exposure was 10 or more days, suggesting reversibility. The requirement for O(2) in seed development is independent of CO(2) concentration with similar results produced by subambient O(2) combined with ambient CO(2), elevated CO(2) up to 2000 mul/l or depressed levels of CO(2) with the CO(2)/O(2) ratio as in air. An elevated O(2) atmosphere containing 40% O(2) and ambient or elevated CO(2) inhibited total growth but did not affect the balance of vegetative to reproductive growth.We conclude that an unknown reaction or process requiring at least atmospheric concentrations of O(2) but independent of CO(2) in contrast to photorespiration is necessary for optimization of all phases of reproductive growth and the effect is reversible for exposures of up to 3 days but not for exposures of 10 days or more. We propose that this O(2) phenomenon may be the result of a unique physical process or chemical reaction associated with translocation and accumulation of assimilates in reproductive structures.

Journal Article↗