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Biomedical subjects

J F Robinson

Publications and source records attributed to J F Robinson.

17 recordsLinked to original sources
PubMed2001

Conservation of chromosome 1 in turtles over 66 million years.

Fluorescence in situ hybridization of a whole chromosome 1-specific probe from the yellow-bellied slider turtle (Trachemys scripta) to cells from four other species of turtle ranging from a desert tortoise to a loggerhead sea turtle resulted in specific and exclusive hybridization to chromosome 1 in all five species. Previous observations of conservation in the giemsa banding pattern and chromosome morphology and number among turtles are thus extended to the DNA sequence level, revealing a cytogenetic stability of chromosome 1 in these turtles during the past 66-144 million years. This contrasts with the situation for various hominoid species where, in many instances, extensive chromosomal rearrangements have been reported in one third of that time period. Our probe, which was prepared by microdissecting whole chromosomes from embryonic T. scripta fibroblasts and amplifying using DOP-PCR, is the first report of a whole-chromosome FISH probe for any reptile.

Animals↗
PubMed1999

Nonrandom degradation of DNA in human leukemic cells during radiation-induced apoptosis.

In many cells, the process of apoptosis is accompanied by endonuclease-mediated double-strand cleavage of DNA between nucleosomes, resulting in the production of discrete fragments of 200 bp or multiples thereof. To address the question of whether this endonuclease attack occurs randomly or nonrandomly along chromosomes, we first constructed chromosome fluorescence in situ hybridization probes from the 200- and 400-bp fragments from gamma-irradiated apoptotic human T cells along with similar-sized probes from randomly sheared DNA of nonirradiated cells. These probes were compared for their binding along normal human metaphase chromosomes after fluorescence in situ hybridization with and without the presence of unlabeled total human blocking DNA. The addition of blocking DNA to the apoptotic probes revealed a nonrandom pattern of hybridization that was not observed for the nonirradiated control probes. The most obvious areas of selective binding occurred around the centromeric and other heterochromatic regions along the chromosome arms, such as the long (q arm) of the Y chromosome. The converse of this experiment was also carried out. DNA probes from heterochromatic and euchromatic regions of the human Y chromosome were hybridized onto slot blots of apoptotic ladder-sized and randomly sheared nonirradiated human T-lymphocyte DNA. The slot blot results showed that for an equal mass of ladder-sized apoptotic DNA and randomly sheared nonirradiated control DNA, the apoptotic DNA sample contains a relatively larger proportion of Y heterochromatin DNA sequences (approximately 2.5-fold). Together, these results indicate that apoptosis-mediated endonuclease attack does not occur randomly in the genome but occurs preferentially in heterochromatin.

Acute Disease↗
PubMed1998

Brachymetatarsia: congenitally short third and fourth metatarsals treated by distraction lengthening--a case report and literature summary.

Brachymetatarsia is an uncommon condition, and when present, it is usually asymptomatic. A case report demonstrating the use of distraction lengthening for symptomatic multiple congenital short metatarsals is presented. A 15-year-old female with congenital short third and fourth metatarsals was treated for painful transfer lesions under the second and fifth metatarsal heads and a secondary hallux valgus deformity. Surgical correction with a chevron osteotomy, soft tissue reconstruction of the second toe, and distraction lengthening of the third and fourth metatarsals was performed. Three years after treatment, the patient has an excellent clinical correction, with no evidence of recurrent transfer lesions. To our knowledge, this is the first report demonstrating the use of distraction lengthening without supplemental bone graft for multiple short metatarsals in a single extremity.

Abnormalities, Multiple↗
PubMed1997

Blind atrial pacing for patients with sinus node disease who develop atrial fibrillation during permanent pacemaker implantation.

During a 6-year period, six of 110 patients implanted with AAI pacemakers for sick sinus syndrome developed atrial fibrillation at the time of pacemaker implantation (5.5%). In all cases a passive fixation lead was sited in the right atrial appendage, its stability being ensured by rotation of the lead and phrenic nerve stimulation excluded by pacing at 10 V. One patient remained in chronic atrial fibrillation. In the other five, who subsequently reverted to sinus rhythm, atrial P-wave sensing and lead threshold values were satisfactory, allowing programming of the pacemaker output down to 2.5 V to conserve the battery. One out of these five patients continued to have intermittent atrial fibrillation. We conclude that in sick sinus syndrome, atrial fibrillation complicates AAI pacemaker implantation procedure in 5.5% of cases. As an alternative to an unplanned general anaesthetic to cardiovert the patient, it is reasonable to implant an atrial lead in the right atrial appendage in the expectation of a spontaneous reversion to sinus rhythm with a good lead threshold and P-wave sensing. In contrast to inappropriate pacing of the right ventricle in VVI mode, this strategy avoids pacemaker syndrome and reduces the risk of subsequent attacks of atrial fibrillation.

Atrial Fibrillation↗
PubMed1997

An ionizing radiation-sensitive CHO mutant cell line: irs-20. IV. Genetic complementation, V(D)J recombination and the scid phenotype.

The genetic defect responsible for hypersensitivity of Chinese hamster ovary (CHO) irs-20 cells to ionizing radiation was found to be recessive in nature and could be complemented to produce wild-type radiosensitivity in irs-20/human hybrids. The radiosensitivities of six hybrid clones were determined based on their colony-forming ability under continuous irradiation at 6 cGy/h. A parallel cytogenetic analysis revealed a concordance between the presence or absence of human chromosome 8 and the resistant or sensitive phenotype. Confirming evidence was obtained using human chromosome 8-specific PCR primers. Positive amplification was obtained in hybrids with wild-type radiosensitivity, while no amplification was obtained in sensitive hybrids. Complementation analysis between radiosensitive CHO irs-20 and murine scid cell lines was carried out to determine whether the defects leading to their ionizing radiation hypersensitivity could be corrected by genetic complementation in the hybrids. Complementation did not occur. A transient V(D)J recombination assay after the introduction of the RAG1 and RAG2 genes indicated that the V(D)J recombination ability of the CHO irs-20 cells was about 10% of that for the CHO wild-type cells for signal join formation with an 80% joining fidelity and only 3% of the parental level for coding join formation. These data show that murine scid and irs-20 mutant hamster cells fall into the same complementation group and show similar defects in V(D)J recombination.

Animals↗
PubMed1995

Perforation of the great vessels during central venous line placement.

BACKGROUND: Placement of central venous lines for the administration of a variety of therapies has become common practice. The most severe complication of this procedure is perforation of a large vessel, with bleeding, infusion of fluids into an extravascular site, and death. It is not clear from currently available data how often this occurs, what risk factors are associated, and how this complication can be avoided. METHODS: We reviewed the records of all patients who were identified as having perforation of a major vessel during central venous line placement occurring between 1986 and 1993 at the University Hospital, the major teaching facility of the University of Colorado Health Sciences Center, Denver. Data collected included the age and sex of the patient, diagnosis, type of catheter and site of placement, operator means and time to the diagnosis of perforation, and outcome. RESULTS: Eleven such complications were identified and 10 of them are reviewed in detail. The overall incidence was less than 1%. Most complications occurred when the right subclavian vein approach was attempted, and they were thought to result from guidewire kinking during advancement of a vessel dilator. All medical specialties and levels of training were involved. Four of 10 patients died of immediate or subsequent complications of the perforation. CONCLUSIONS: Perforation of a great vessel is an uncommon, but often fatal, complication of central venous line placement. It occurs most often, when using the right subclavian vein approach, from guidewire kinking. Physicians performing this procedure should have formal training in central venous catheterization and be aware of this complication, its presumed cause, diagnosis, and treatment.

Adult↗
PubMed1987

Exercise testing in the diagnosis of sick sinus syndrome in the elderly: implications for treatment.

Twenty-three elderly patients underwent treadmill exercise testing to fatigue; 11 patients had sick sinus syndrome (7 males, 4 females; age range 71-91 years; mean, 78 years); 12 elderly persons were controls (5 males, 7 females; age range 70-93 years; mean, 76 years). All were euthyroid. The study showed that patients with sick sinus syndrome compared with the control group demonstrated a lower resting heart rate, a smaller increase in heart rate during exercise, poorer exercise tolerance, and differences in heart rate during the recovery phase. The value of the effort test in relation to the diagnosis of sick sinus syndrome is discussed, together with its possible implications in the choice of pacemaker.

Aged↗
PubMed1986

Failure of Quintech Tx pacemaker caused by loss of stimulus-T interval shortening during exercise.

A 74 year old man with a Quintech Tx pacemaker experienced a reduction in his exercise capacity because his heart rate failed to increase with effort. This was shown to be caused by the failure of the interval between the delivered stimulus and evoked T wave to decrease during effort where previously it had done so. Although the stimulus-T interval did not change during exercise, it did decrease in response to isoprenaline infusion and in response to pacing the heart at increasing rates. Catecholamine concentrations increased during exercise and the patient had normal thyroid function.

Aged↗
PubMed1982

A placebo controlled study of the cardiovascular effects of fluvoxamine and clovoxamine in human volunteers.

1 Fluvoxamine and clovoxamine, two new potential antidepressants were given to 27 healthy male volunteers in a double-blind, placebo controlled, three-way crossover study. 2 Neither compound affected the electrical intervals of 24 h ambulant electrocardiographic monitoring with the exception of a small increase in R-R interval. 3 There were no changes in blood pressure measurements. 4 The only notable unwanted symptom was nausea for both fluvoxamine and clovoxamine.

Antidepressive Agents↗
PubMed1979

Psychological rehabilitation after myocardial infarction.

The value of psychological counselling in rehabilitating patients after myocardial infarction was assessed. A total of 143 men who had recently had a myocardial infarction were randomly allocated to either a group receiving intensive rehabilitation or a control group, their outcome being examined after six months. Patients with neurotic, introverted personalities had a poor outcome in the control group but a satisfactory outcome when rehabilitated. Neurotic personalities responded to help, and rehabilitative measures did not increase neurosis. In addition all patients with a negative attitude towards their illness and future had a poor outcome but those with a positive attitude did well. Selection by simple methods of patients who would benefit from psychological rehabilitation seems desirable.

Adult↗