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Biomedical subjects

R W Hardy

Publications and source records attributed to R W Hardy.

At least 73 records · Page 4Linked to original sources
PubMed1984

Cytogenetic analysis of a segment of the Y chromosome of Drosophila melanogaster.

Males carrying a large deficiency in the long arm of the Y chromosome known to delete the fertility gene kl-2 are sterile and exhibit a complex phenotype: (1) First metaphase chromosomes are irregular in outline and appear sticky; (2) spermatids contain micronuclei; (3) the nebenkerns of the spermatids are nonuniform in size; (4) a high molecular weight protein ordinarily present in sperm is absent; and (5) crystals appear in the nucleus and cytoplasm of spermatocytes and spermatids. In such males that carry Ste+ on their X chromosome the crystals appear long and needle shaped; in Ste males the needles are much shorter and assemble into star-shaped aggregates. The large deficiency may be subdivided into two shorter component deficiencies. The more distal is male sterile and lacks the high molecular weight polypeptide; the more proximal is responsible for the remainder of the phenotype. Ste males carrying the more proximal component deficiency are sterile, but Ste+ males are fertile. Genetic studies of chromosome segregation in such males reveal that (1) both the sex chromosomes and the large autosomes undergo nondisjunction, (2) the fourth chromosomes disjoin regularly, (3) sex chromosome nondisjunction is more frequent in cells in which the second or third chromosomes nondisjoin than in cells in which autosomal disjunction is regular, (4) in doubly exceptional cells, the sex chromosomes tend to segregate to the opposite pole from the autosomes and (5) there is meiotic drive; i.e., reciprocal meiotic products are not recovered with equal frequencies, complements with fewer chromosomes being recovered more frequently than those with more chromosomes. The proximal component deficiency can itself be further subdivided into two smaller component deficiencies, both of which have nearly normal spermatogenic phenotypes as observed in the light microscope. Meiosis in Ste+ males carrying either of these small Y deficiencies is normal; Ste males, however, exhibit low levels of sex chromosome nondisjunction with either deficient Y. The meiotic phenotype is apparently sensitive to the amount of Y chromosome missing and to the Ste constitution of the X chromosome.

Animals↗
PubMed1984

High-performance liquid chromatographic measurement of cyclophosphamide in serum.

The analysis of cyclophosphamide [N,N-bis(2-chlorethyl)-tetrahydro-2H-1,3,2-oxazaphosphorin-2-amine -2-oxide] by high-performance liquid chromatography using ultraviolet detection is described. The method will enable measurement of serum concentrations of cyclophosphamide over a period of approximately 24 h after a dose of 150 mg, and requires 1 ml of serum. The between-day precision of the assay at concentrations of 0.3, 1.0, and 15.0 mg/L generated coefficients of variation of 11.8, 12.2, and 7.7%, respectively. Percentages of analytical recovery of cyclophosphamide and internal standard (5-ethyl-5-p-tolylbarbituric acid) were 63 and 73%, respectively. Preliminary data providing the half-life for two patients with normal renal function are presented.

Chemical Phenomena↗
PubMed1984

Role of amides, amino acids, and ureides in the nutrition of developing soybean seeds.

The various nitrogenous solutes important to embryo development in symbiotic soybean plants were determined during the midpodfilling stage. Glutamine was the principal form of nitrogen, contributing 55% of the embryo nitrogen requirement. Asparagine was the second most important, contributing 20%. The ureides allantoin and allantoic acid directly contributed only insignificantly to the total nitrogen requirement of the embryo. These conclusions were based upon analyses of tissue extracts, translocation studies of radiolabeled solutes, analysis of in vivo seed coat exudate collected from the freespace of attached, surgically altered seeds, and the in vitro culture of isolated immature soybean embryos.

Journal Article↗
PubMed1984

Experimental determination of the respiration associated with soybean/rhizobium nitrogenase function, nodule maintenance, and total nodule nitrogen fixation.

The total metabolic cost of soybean (Glycine max L. Mer Clark) nodule nitrogen fixation was empirically separated into respiration associated with electron flow through nitrogenase and respiration associated with maintenance of nodule function.Rates of CO(2) evolution and H(2) evolution from intact, nodulated root systems under Ar:O(2) atmospheres decreased in parallel when plants were maintained in an extended dark period. While H(2) evolution approached zero after 36 hours of darkness at 22 degrees C, CO(2) evolution rate remained at 38 degrees of the rate measured in light. Of the remaining CO(2) evolution, 62% was estimated to originate from the nodules and represents a measure of nodule maintenance respiration. The nodule maintenance requirement was temperature dependent and was estimated at 79 and 137 micromoles CO(2) (per gram dry weight nodule) per hour at 22 degrees C and 30 degrees C, respectively.The cost of N(2) fixation in terms of CO(2) evolved per electron pair utilized by nitrogenase was estimated from the slope of H(2) evolution rate versus CO(2) evolution rate. The cost was 2 moles CO(2) evolved per mole H(2) evolved and was independent of temperature.In this symbiosis, nodule maintenance consumed 22% of total respiratory energy while the functioning of nitrogenase consumed a further 52%. The remaining respiratory energy was calculated to be associated with ammonia assimilation, transport of reduced N, and H(2) evolution.

Journal Article↗
PubMed1984

Calorimetry of nitrogenase-mediated reductions in detached soybean nodules.

Heat evolved by isolated soybean (Glycine max cv Clark) nodules was measured to estimate more directly the metabolic cost associated with the symbiotic N(2) fixation system. A calorimeter constructed by modifying standard laboratory equipment allowed measurement on 1 gram of detached nodules under a controlled gas stream. Simultaneous gas balance and heat output determinations were made.There was major heat output by nodules for all of the nitrogenase substrates tested (H(+), N(2), N(2)O, and C(2)H(2)) further establishing the in vivo energy inefficiency of biological N(2) fixation. Exposure to a short burst of 100% O(2) partially inactivated nitrogenase to permit calculations of heat evolved per mole of substrate reduced. The specific rate of heat evolution for H(+) reductions was 171 +/- 6 kilocalories per mole H(2) evolved in an Ar-O(2) atmosphere, that for N(2) fixation was 784 +/- 26 kilocalories per mole H(2) evolved and N(2) fixed, and that for C(2)H(2) reduction was 250 +/- 12 kilocalories/mole C(2)H(4) formed. When the appropriate thermodynamic parameters are taken into account for the different substrates and products, a DeltaH' of -200 kilocalories per mole 2e(-) is shown to be associated with active transfer of electrons by the nitrogenase system. These values lead to a calculated N(2) fixation cost of 9.5 grams glucose per gram N(2) fixed or 3.8 grams C per gram N(2), which is in close agreement with earlier calculations based on nodular CO(2) production.

Journal Article↗
PubMed1984

Nuclear magnetic resonance of the spine: clinical potential and limitation.

Magnetic resonance can visualize the vertebral bodies, discs, neural structures, cerebrospinal fluid (CSF), neural foramina, and extradural structures in the sagittal, axial, and coronal planes. The normal nucleus pulposus can be differentiated from the anulus and changes associated with degeneration. Infection, trauma, and neoplastic conditions can be identified. The signal intensity of the CSF relative to extradural and neural structures can be increased to provide evaluation of the size and configuration of the contents of the thecal sac without the use of an intrathecal contrast medium. Impingement by disc, tumors, fracture segments, and expansile masses can then be accurately evaluated. It is the most accurate modality for the evaluation of the foramen magnum, Chiari malformation, syringomyelia, infection, and degeneration of intervertebral discs. It can identify paravertebral soft tissue and bony changes when plain films and computed tomographic (CT) studies are negative or equivocal. Not only can lesions be localized, but significant information regarding the nature of the process can be obtained. Using variations of the spin-echo technique with appropriate T1 and T2-weighted images, magnetic resonance can produce tissue contrast distinctions not possible with CT scans or conventional angiography.

Arteriovenous Malformations↗
PubMed1984

Jugular foramen schwannomas.

Thirteen patients with schwannomas of the jugular foramen were operated on at the Cleveland Clinic between 1974 and 1983. The authors' experience in managing these rare tumors is presented. Three major growth patterns of jugular foramen schwannoma were seen, and it is postulated that the position of the tumor depends on its point of origin from the nerves as they pass through the pars nervosa of the jugular foramen. The more distal lesions will expand inferiorly out of the base of the skull, and the more proximal lesions will enlarge into the posterior fossa. Tumors in the mid region will tend to expand primarily into bone. The schwannoma was primarily intracranial in six patients. In five patients the tumor expanded the bone at the base of the skull, with only a small intracranial component, and in two patients the tumor was primarily extracranial, with a small extension into the bone or posterior fossa. The presentation of the patients varied according to the tumor growth pattern. Deafness, vertigo, and ataxia were present in all patients with a major intracranial component, and in most of these there were only minimal deficits of the jugular foramen nerves. By contrast, lower cranial nerve involvement, including hoarseness and weakness of the trapezius and sternocleidomastoid muscles, occurred in patients in whom the tumor was primarily, within the bone or extracranial. Three of the five patients with the major component of the schwannoma within the bone also had deafness. Symptomatic history was longest in those with tumor mainly involving the bone at the base of the skull, and shortest in patients with entirely extracranial tumor. Surgical resection was accomplished with a joint neurosurgical-otological approach, usually combining a posterior fossa exploration with either a translabyrinthine transcochlear or infralabyrinthine procedure. The exact nature of the operation depended upon the presence of intracranial tumor and on the extent of bone or extracranial involvement. Total excision was performed in all cases. There was no operative mortality, and surgery resulted in loss of function of the ninth, 10th, and 11th cranial nerves in most patients. The major postoperative morbidity consisted of swallowing difficulties and sputum aspiration.

Adult↗
PubMed1983

Enhanced Mineral Uptake by Zea mays and Sorghum bicolor Roots Inoculated with Azospirillum brasilense.

Inoculation of corn (Zea mays) seeds with Azospirillum brasilense strain Cd or Sp 7 significantly enhanced (30 to 50% over controls) the uptake of NO(3), K, and H(2)PO(4) into 3- to 4-day- and 2-week-old root segments. No gross changes in root morphology were observed; altered cell arrangement in the outer four or five layers of the cortex was seen in photomicrographs of cross sections of inoculated corn roots. The surface activity involved in ion uptake probably increased, as shown by the darker staining by methylene blue of the affected area. Shoot dry weight increased 20 to 30% in inoculated plants after 3 weeks, presumably by enhancement of mineral uptake. Corn and sorghum plants grown to maturity on limiting nutrients in the greenhouse showed improved growth from inoculation approaching that of plants grown on normal nutrient concentrations. Enhanced ion uptake may be a significant factor in the crop yield enhancement reported for Azospirillum inoculation.

Journal Article↗
PubMed1983

N(2) Fixation by Azospirillum brasilense and Its Incorporation into Host Setaria italica.

Growth and nitrogen fixation were followed during the life cycle of Setaria italica (foxtail millet) inoculated with Azospirillum brasilense in controlled-environment growth chambers. The plants were fertilized at seeding with a limiting amount of combined nitrogen and maintained with an N-free mineral solution. During maturation of the plants, substantial nitrogenase activity, measured by acetylene reduction, developed in the rhizosphere, with total fixation estimated to be equivalent to 20% of the N in the inoculated plants. The peak of this activity coincided with depletion of soluble nitrogen from the system, which in turn was reflected by a sharp decrease in the nitrate reductase activity of the leaves. A. brasilense was found in association with the root populations at 8 x 10 cells per gram of dry weight. An increase in shoot growth occurred at this time, but no significant increase in total plant nitrogen could be demonstrated. N(2) enrichment experiments confirmed that fixation was occurring, but only about 5% of the nitrogen fixed by A. brasilense was incorporated into the plants within 3 weeks. There was thus no evidence of direct bacterium-to-plant transport of fixed nitrogen, but rather a slow transfer suggesting the gradual death of bacteria and subsequent mineralization of their nitrogen, at least under growth-room conditions.

Journal Article↗
PubMed1983

Computed tomographic, myelographic, and operative findings in patients with suspected herniated lumbar discs.

Fifty patients presenting with a suspected herniated lumbar intervertebral disc were evaluated with sector computed tomography (CT). Excluded from this series were patients with prior lumbar laminectomy or a clinical diagnosis of lumbar canal stenosis. Forty-six of the patients also underwent preoperative lumbar myelography. All patients subsequently underwent laminectomy. In 40 patients (80%), CT was positive. In the remaining 10 patients (20%), it was negative; in this group the myelogram correctly predicted the lesion in 8 (80%). Sector CT correctly predicted the nature of the lesion in 24 patients (48%), was incorrect in 14 (28%), and gave incomplete findings in 12 (24%). CT was most accurate when it demonstrated a disc protrusion as the only finding. In this group, sector CT correctly predicted the operative findings in 24 of 25 patients (96%). CT was less accurate when spondylitic compression was diagnosed. This study suggests that sector CT is a useful test in the evaluation of patients with sciatica and that, when a soft herniated disc is demonstrated on CT, myelography may be omitted.

Adult↗
PubMed1983

Trigeminal neuralgia treated by radiofrequency coagulation.

Ninety-six patients underwent percutaneous radiofrequency coagulation (RC) of the Gasserian ganglion for relief of trigeminal neuralgia between 1973 and 1978. Fifty-two percent of patients who were followed for 5 years were free of recurrence after a single RC procedure. Factors predicting clinical results were sought from initial historical and demographic data. Age, sex, duration of illness, and previous response to medication were unrelated to outcome. Patients previously treated by open surgery appeared to receive less benefit from subsequent RC. The RC procedure seemed more effective in the treatment of patients with classical tic douloureux than in those with atypical features. The degree of sensory loss created by RC was associated with the clinical outcome. Patients acquiring dense sensory deficits demonstrated a reduced risk of recurrence (p = 0.006): 25% of patients with dense sensory loss and 55% of those with a partial deficit developed a recurrence by 5 years, whereas all patients without initial sensory loss suffered a recurrence by 5 years.

Adult↗
PubMed1982

Structural genes on the Y chromosome of Drosophila melanogaster.

Testis proteins of Drosophila melanogaster deficient for six different Y-chromosome regions were fractionated by means of a sodium dodecyl sulfate/polyacrylamide gel system designed to separate high molecular weight polypeptides (Mr, greater than 200,000). Analysis of the banding patterns indicates that the three regions containing fertility genes kl-2, kl-3, and kl-5 are responsible for three different high molecular weight polypeptides. Several observations indicate that these polypeptides are structural components of the sperm axoneme. They are present in seminal vesicles, which are highly enriched for mature sperm. They are first detected during development at a time when the first spermatids are elongating. Finally, deletion of either kl-5 or kl-3 leads to the absence of the outer dynein arm of the peripheral doublets of the axoneme. Although absence of the kl-2 region eliminates the third polypeptide, an associated structural defect in the axoneme has yet to be identified. The three polypeptides are in the Mr 300,000-350,000 range, and their mobilities are similar to those of dynein polypeptides from Chlamydomonas axonemes. Experiments using dosage variation and a temperature-sensitive sterile mutation in kl-5 suggest that the Y-chromosome regions contain the coding sequences for the polypeptides.

Aneuploidy↗
PubMed1982

Sector computed tomographic spine scanning in the diagnosis of lumbar nerve root entrapment.

The diagnosis of lumbar nerve root entrapment was made by sector computed tomography (CT) scanning in 25 patients whose myelograms were normal at the site of the CT scan abnormalities. Sector CT scanning demonstrates preoperatively which neural foramina are narrow. This information, correlated with the patient's history and physical examination, indicates which foramina should be operated on and prevents unnecessary exploration of normal neural foramina. CT findings were confirmed surgically in 14 patients. Eleven of these 14 patients had excellent postoperative results and remain pain free.

Adult↗
PubMed1982

Encouraging surgical results in walking patients with epidural metastases.

The management of epidural metastases is in a state of controversy between combined surgical and radiation treatment and treatment by radiation alone. Review of the literature shows that one group, patients who are ambulatory before treatment, have been studied rarely. We analyzed our last 15 years of experience at the Cleveland Clinic and found 39 patients who were ambulatory preoperatively; 84% of these walked during the short term follow-up and 93% of the 1-year survivors walked. These data suggest that surgery has an important role in the management of ambulatory patients.

Epidural Space↗