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Biomedical subjects

K Hardy

Publications and source records attributed to K Hardy.

At least 109 records · Page 6Linked to original sources
PubMed1989

The human blastocyst: cell number, death and allocation during late preimplantation development in vitro.

The development of 181 surplus human embryos, including both normally and abnormally fertilized, was observed from day 2 to day 5, 6 or 7 in vitro. 63/149 (42%) normally fertilized embryos reached the blastocyst stage on day 5 or 6. Total, trophectoderm (TE) and inner cell mass (ICM) cell numbers were analyzed by differential labelling of the nuclei with polynucleotide-specific fluorochromes. The TE nuclei were labelled with one fluorochrome during immunosurgical lysis, before fixing the embryo and labelling both sets of nuclei with a second fluorochrome (Handyside and Hunter, 1984, 1986). Newly expanded normally fertilized blastocysts on day 5 had a total of 58.3 +/- 8.1 cells, which increased to 84.4 +/- 5.7 and 125.5 +/- 19 on days 6 and 7, respectively. The numbers of TE cells were similar on days 5 and 6 (37.9 +/- 6.0 and 40.3 +/- 5.0, respectively) and then doubled on day 7 (80.6 +/- 15.2). In contrast, ICM cell numbers doubled between days 5 and 6 (20.4 +/- 4.0 and 41.9 +/- 5.0, respectively) and remained virtually unchanged on day 7 (45.6 +/- 10.2). There was widespread cell death in both the TE and ICM as evidenced by fragmenting nuclei, which increased substantially by day 7. These results are compared with the numbers of cells in morphologically abnormal blastocysts and blastocysts derived from abnormally fertilized embryos. The nuclei of arrested embryos were also examined. The number of TE and ICM cells allocated in normally fertilized blastocysts appears to be similar to the numbers allocated in the mouse. Unlike the mouse, however, the proportion of ICM cells remains higher, despite cell death in both lineages.

Blastocyst↗
PubMed1988

Effect of low-dose doxorubicin on calcium content and norepinephrine response in rat aorta.

Doxorubicin (DXR) is a common antineoplastic agent whose clinical utility is limited by development of a dose-related cardiomyopathy. Recent studies demonstrating DXR toxicity in skeletal muscle suggest that this compound may in fact be a general depressant of muscle function. Although previous studies have reported possible indirect actions of DXR on blood vessels, we have investigated the direct effects of this agent on vascular smooth muscle. Chronic, low-dose treatment of rats with intraperitoneal DXR (12 mg/kg total dose over 4 weeks) had no significant effect on body or heart weight, left ventricular water or calcium content, or aortic water or calcium content. Contractile responses to norepinephrine of thoracic aortic strips taken from DXR-treated rats were attenuated by this treatment, and sensitivity (EC50) of these strips to norepinephrine was significantly reduced compared to controls. These results suggest that DXR may have physiological effects on vascular smooth muscle function at doses which produce no signs of toxicity in cardiac muscle.

Animals↗
PubMed1987

Preimplantation diagnosis of deficiency of hypoxanthine phosphoribosyl transferase in a mouse model for Lesch-Nyhan syndrome.

Male mice embryos deficient in hypoxanthine phosphoribosyl transferase (HPRT), derived from heterozygous (carrier) females and normal males, were diagnosed by biochemical microassay of HPRT activity in a single cell isolated from the eight-cell preimplantation embryo. The sampled embryos were transferred to recipient mothers and examined on the 14th day of gestation to confirm the accuracy of the preimplantation diagnosis. The diagnosis was sufficiently rapid that freezing of the embryos before transfer was not necessary. Of the embryos diagnosed as HPRT negative all 4 that grew into fetuses were correctly identified as HPRT-deficient males.

Animals↗
PubMed1987

Takayasu's arteritis associated with crescentic glomerulonephritis.

We describe the initial course and followup of a 16-year-old white female patient who presented in 1983 with aortitis and rapidly progressive renal failure. Renal biopsy revealed crescentic glomerulonephritis. Segmental occlusions of the distal aorta and both common iliac arteries were demonstrated on aortography. Initially, her renal function and arterial occlusions markedly improved with pulse prednisolone therapy, but 34 months later, the glomerulonephritis and aortitis worsened. This case report, the first of its kind, documents both the association of Takayasu's arteritis with crescentic glomerulonephritis and a marked, though incomplete, response to pulse therapy.

Adolescent↗
PubMed1987

Clinical features, survival rate, and prognostic factors in young adults with cystic fibrosis.

The medical records of 142 patients with cystic fibrosis were reviewed. The patient group included 78 males and 64 females; three patients were black. Periods of observation ranged from two to 25 years (mean, 14.5 years). The analysis focused on clinical evaluation at age 18 years and included information gained at an earlier age. Evaluation at age 18 years was based on Shwachman and Kulczycki's (S-K) scoring system, Brasfield chest roentgenographic scoring system, pulmonary function measurements, height-adjusted weight percentile, sputum bacteriologic results, number of hospitalizations for treatment of pulmonary infections prior to the age of 18 years, time of onset of clubbing, and frequency of complications. There were no significant differences between the sexes in clinical features. Median survival from the time of diagnosis to the conclusion of the study period (1955 to 1984) was 22 years for females and 25 years for males (NS). Median length of survival beyond the age of 18 years was eight years for females and 12 years for males (NS). Stepwise logistic regression and Cox regression analysis applied to 11 variables identified the S-K clinical score at 18 years of age as the best predictor of survival to the age of 23 years. The median durations of survival after the age of 18 years for patients with clinical scores of 30 to 49, 50 to 64, and 65 to 75 at age 18 were five, seven and a half, and 12 years, respectively (p less than 0.0001). Low clinical score, low weight percentile, and Pseudomonas cepacia colonization of the lower respiratory tract at the age of 18 years indicated a poor prognosis. On the other hand, high clinical score, good weight percentile, and colonization with Staphylococcus aureus alone were likely to be found in patients with mild disease and an increased likelihood of long-term survival with preserved pancreatic function.

Adolescent↗
PubMed1987

Rescue of developmental lens abnormalities in chimaeras of noncataractous and congenital cataractous mice.

In the study of the lens of a congenital cataractous mouse mutant (CAT), it has been shown that a loss of growth regulation at the cellular level causes gross lens abnormalities. The phenotypic characteristics of the cataractous mouse lens are similar to those seen in human congenital cataract and thus serves as a model system for medical research. In this present investigation, we have demonstrated that the abnormalities of the congenital cataractous lens can be rescued by forming chimaeras between DBA/2 (a noncataractous strain of mouse) and the CAT mutant. This report describes the histological, cellular and biochemical analysis of the resultant chimaeric eyes, and discusses possible mechanisms by which these results were achieved.

Animals↗
PubMed1987

Metabolism of glucose by human embryos.

Glucose turnover, as measured by CO2 production, lactate accumulation and carbon incorporation from [U-14C]glucose as sole energy substrate, was low on the 2nd day of culture of human embryos resulting from in-vitro fertilization but above that of unfertilized oocytes. In general, all parameters of metabolism increased substantially during the following 2 days of development but the rate of increase in lactate production was greater than that of CO2, especially between Days 3 and 4. Within developing embryos, no correlation was evident between the metabolic turnover of glucose and the method of patient stimulation, the morphological quality of embryos or the apparent rate of cleavage in culture. The results indicate that, before Day 3 of development, glucose is not effective as an energy source for the human embryo because of a blockade to glycolysis similar to that in mouse embryos.

Blastocyst↗
PubMed1986

Automated thermometric enzyme immunoassay of human proinsulin produced by Escherichia coli.

We have determined and monitored the production and release of human proinsulin by genetically engineered Escherichia coli cells. Several M9 media samples were analyzed sequentially after centrifugation with the aid of a rapid automated flow-through thermometric enzyme-linked immunosorbent assay (TELISA) system. The response time was 7 min after sample injection and a single assay was complete after 13 min. Insulin concentrations in the range of 0.1-50 micrograms/ml could be determined. The TELISA method correlated well with conventional radioimmunoassay determinations. Standard curves were reproducible over a period of several days even when the immobilized antibody column was stored at 25 degrees C in the enzyme thermistor unit. Thus, immediate assay start up was possible.

Enzyme-Linked Immunosorbent Assay↗
PubMed1986

The role of the T3/antigen receptor complex in T-cell activation.

The role of the T3/antigen receptor complex is summarized by the diagram presented in Figure 4. Signals transmitted through T3/Ti activate a phosphodiesterase. This enzyme acts on its substrate PIP2 to generate two important mediators, IP3 and diacylglycerol. IP3 mobilizes calcium from bound intracellular stones. This increase in [Ca2+]i is one intracellular signal which, in conjunction with others, induces expression of lymphokine genes by influencing pretranslational, presumably transcriptional, events. Several problems remain. Which of the five molecules in the T3/Ti complex serves as the effector molecule in the transmembrane signaling process is not known. Which molecules serve to link T3/Ti to the phosphodiesterase enzyme is under investigation. The role diacylglycerol protein kinase C and other mediators play in signalling activation is not established. Finally, for those events occurring after the early events pictured in Figure 4 that result in gene activation, the sequence is a black box. Approaches to address each of these questions are available, and answers should be forthcoming.

Animals↗
PubMed1983

Formation of proinsulin by immobilized Bacillus subtilis.

There has been an increasing interest in the use of immobilized cells for the production of pharmaceuticals as well as for products such as high fructose syrup or ethanol. Some of these compounds are now produced on an industrial scale whereby the cells are used in a resting or growing state or in a nonviable form as natural carriers of the enzyme(s) involved in the synthesis. The advantages of immobilized cell technology should also apply to microorganisms modified by recombinant DNA techniques to produce a variety of eukaryotic proteins such as hormones. We describe here the properties of immobilized Bacillus subtilis cells carrying plasmids encoding rat proinsulin. Cell proliferation normally coupled to DNA replication is undesirable in immobilized cell systems as "clogging' of the system occurs due to cells growing outside the beads. Therefore, different ways were investigated to inhibit cell division while allowing continued protein synthesis. We found that the addition of certain antibiotics in the growth medium, such as novobiocin which inhibits DNA replication, fulfills these requirements, allowing proinsulin synthesis and excretion to take place over a period of several days.

Bacillus subtilis↗
PubMed1982

Expression in Escherichia coli of a staphylococcal gene for resistance to macrolide, lincosamide, and streptogramin type B antibiotics.

Plasmid pBD9, which comprises two plasmids from Staphylococcus aureus, pE194 and pUB110, was joined to plasmid pBR322 by in vitro recombination to form plasmid pKH80. The ermC gene of plasmid pE194 confers inducible resistance to macrolide, lincosamide, and streptogramin type B antibiotics. When pKH80 was transferred to Escherichia coli K-12, the bacteria became resistant to several of these antibodies.

Anti-Bacterial Agents↗