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Biomedical subjects

J C Hart

Publications and source records attributed to J C Hart.

At least 37 records · Page 2Linked to original sources
PubMed1990

A comparison of the wound integrity produced by various suture patterns in penetrating keratoplasty: a cadaver eye model.

We tested the watertightness of wound closure in penetrating keratoplasty as a function of suture pattern by performing a 7.5-mm penetrating keratoplasty on 12 human cadaver eyes using a variety of suture patterns. We then tested wound integrity by hydrostatically raising the intraocular pressure. In this cadaver eye model, we demonstrated that running sutures produced better wound closure than interrupted sutures using the same number of bites. A 16-bite running or a combined running-interrupted pattern produced more than ample watertightness in penetrating keratoplasty wound closure.

Cadaver↗
PubMed1990

Suture patterns and corneal graft rotation in the cadaver eye.

Torque and antitorque running sutures as described by Eisner are commonly used in penetrating keratoplasty. We tested the rotational effect of three different 16-bite running suture patterns on eight cadaver eyes, with the following results: (1) the torque pattern rotates the corneal graft counterclockwise by 0.7 +/- 0.1 mm at the wound or 11 degrees; (2) the antitorque pattern rotates the corneal graft clockwise by 0.7 +/- 0.1 mm at the wound or 11 degrees; (3) an intermediate "no torque" pattern, the bites of which form an isosceles triangle, produces no rotational effect. We recommend the use of a "no torque" pattern to minimize corneal graft rotation.

Cadaver↗
PubMed1987

Kappa agonist-induced diuresis: evidence for stereoselectivity, strain differences, independence of hydration variables and a result of decreased plasma vasopressin levels.

Marked diuresis has previously been reported after administration of kappa opioid agonists. The present study shows that this effect is stereospecific; MR-2034 markedly increased urinary output over the dose range 0.08 to 1.25 mg/kg, whereas the opposite isomer, MR-2035, was markedly less potent. Bremazocine increased urinary output in Long-Evans hooded and Sprague-Dawley albino rats as well as lean and fatty Zucker rats. In the lean Zucker and the albino rats, bremazocine produced an inverted U-shaped diuretic dose-effect curve, an effect characteristic of kappa agonists with mu agonist activity. This pattern was not seen with the fatty Zucker rats or the Long-Evans hooded rats. The full kappa agonists bremazocine, ethylketazocine and U-50,488 increased urinary output under three different conditions of hydration: water loaded, normal hydration and water deprived. In contrast, the partial kappa agonists reliably only increase urinary output under the normal hydration condition. The diuretic effects of full and partial kappa agonists correlated with plasma vasopressin levels in water-deprived rats. The full kappa agonists (ethylketazocine, U-50,488, tifluadom and MR-2034) suppressed plasma vasopressin levels below the threshold of detectability of the radioimmunoassay, whereas the partial kappa agonists (nalorphine and butorphanol) suppressed vasopressin levels compared with control values but did not have the efficacy of the full kappa agonists. All these results support the hypothesis that kappa agonists produce their diuretic effect by suppression of plasma vasopressin levels.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1985

Screening of diabetics for retinopathy by ophthalmic opticians.

Diabetes mellitus is a major cause of blindness in England and Wales in those aged between 30 and 64. Photocoagulation can frequently prevent blindness provided the retinopathy is detected at an appropriate stage but unfortunately the benefits are small if the changes are advanced. Early detection of diabetic retinopathy by regular examination is needed. We have shown that ophthalmic opticians have the skill to detect retinal changes at a treatable stage. Out of 844 eye checks, 80 were reported by ophthalmic opticians to justify referral to an ophthalmologist and 20 of these required photocoagulation treatment. Of a sample of 197 patients rechecked by an ophthalmologist reported by ophthalmic opticians not to justify referral, only one needed treatment. With local agreement this system of detecting retinopathy could be easily applied anywhere in the United Kingdom. No extra personnel or facilities are needed.

Blindness↗
PubMed1985

Diuresis and suppression of vasopressin by kappa opioids: comparison with mu and delta opioids and clonidine.

The effects of agonists at kappa, mu and delta opioid receptors were determined on vasopressin levels in water-deprived rats. Bremazocine and U-50, 488 (kappa agonists) markedly suppressed vasopressin levels, whereas morphine and methadone (mu agonists) and metkephamid (a mixed mu and delta agonist) did not suppress vasopressin levels. Likewise, clonidine, a potent diuretic in normally hydrated rats, did not clearly suppress vasopressin levels. Metkephamid was shown to have a modest diuretic effect in normally hydrated rats but not in water-deprived rats. The diuretic effects of bremazocine were blocked completely by simultaneous treatment with desmopressin, a synthetic vasopressin-like analog. Desmopressin also blocked the diuretic effect of a waterload, but only partially attenuated the diuretic effect of clonidine. These results support the hypothesis that kappa opioid agonists produce a diuretic effect by suppressing plasma levels of vasopressin, and at higher doses produce a pattern of urination similar to animals lacking vasopressin. By comparison, mu and delta opioid agonists have little effect on vasopressin levels in water-deprived rats.

Animals↗
PubMed1983

Metastatic periosteal osteosarcoma causing cardiac and renal failure.

The case of a 25-year-old man who had periosteal osteogenic sarcoma with intravascular metastases in unusual locations is reported. The patient presented with acute renal failure, unilateral pulmonary edema, functional mitral stenosis, and low cardiac output. After successful surgical removal of a left atrial metastasis with subsequent improvement in cardiac output, renal function improved only transiently and urinary output varied markedly. At autopsy, metastatic osteogenic sarcoma was discovered within the lumen of the abdominal aorta obstructing both renal arteries. The case is the first report of a neoplasm metastatic to the aorta causing intermittent bilateral renal arterial obstruction; it illustrates the diagnostic difficulties presented by intravascular metastatic disease.

Acute Kidney Injury↗
PubMed1983

Reversed subclavian flap angioplasty for arch coarctation of the aorta.

Subclavian flap repair in infants with coarctation of the aorta has been shown to be superior to end-to-end reconstruction. Aortic arch coarctations in 2 infants were repaired utilizing reversed subclavian flaps with good results. The effectiveness of flap reconstruction in less common forms of aortic coarctation in infants is demonstrated.

Aorta, Thoracic↗
PubMed1983

Subclavian catheterization for the placement of a ventriculovenous shunt.

Repeated nonfunction of the distal end of a ventriculoperitoneal shunt led to an unsuccessful attempt to introduce the distal catheter into the vena cava through the jugular vein. Subclavian catheterization utilizing a cardiac pacemaker introducer set proved to be a simple and effective means of establishing a ventriculovenous shunt.

Catheterization↗
PubMed1982

Novel phenylpiperidine opioid antagonists and partial agonists: effects on fluid consumption.

The effects of five opioid antagonists, a racemate partial agonist and its agonist and antagonist optical isomers were studied on deprivation-induced drinking. All compounds had a phenylpiperidine nucleus. The antagonists produced dose-related decreases in drinking, and the potencies for decreasing drinking correlated with morphine-antagonist doses. The racemic partial agonist and its agonist isomer decreased drinking at doses higher than those which produced marked analgesia. Within the class of phenylpiperidine drugs studied, some had less specificity than naloxone for the mu-receptors as compared to the delta-receptor, but the suppression of drinking was not related to changes in mu-to-delta ratios.

Animals↗
PubMed1981

Accessory diaphragm in an infant.

Accessory diaphragm is a rare congenital abnormality that almost always occurs on the right side and is often associated with cardiovascular anomalies. This paper describes the clinical presentation, radiologic diagnosis, and surgical treatment of the condition. Early recognition and prompt surgical treatment will prevent the chronic pulmonary complications reported in the literature.

Diaphragm↗
PubMed1980

Static perimetric and Amsler chart changes in patients with idiopathic central serous retinopathy.

Macular disturbances in patients with active idiopathic central serous retinopathy can be readily documented by performing Amsler charting or static perimetry, but, as uncertainty exists as to which examination technique is superior for detecting disturbances after a detachment has settled, a study was performed in which patients were investigated by the two methods during the acute, resolving and resolved stages of the disease. All of the patients assessed in the acute phase showed abnormal responses to both forms of examination, but after the oedema fluid absorbed 63% of cases retained abnormal static profiles whereas 81% recorded defects on Amsler charting. Disturbances of retinal function were most apparent on static perimetry testing if the meridian studied corresponded to that intersecting the site at which the focal breakdown of the choroidoretinal barrier had developed and the fovea. The incidence of retinal changes was found to be greater in patients where the oedema resolved slowly.

Adult↗
PubMed1980

Indirect choroidal tears at the posterior pole: a fluorescein angiographic and perimetric study.

Retinal fluorescein angiographic and visual field studies were performed on 10 patients who had developed indireect choroidal tears, these procedures being repeated at intervals until the retinal disturbances stabilised. Fluorographic investigations revealed that a transient breakdown of the choroidoretinal barrier to fluorescein dye could be detected in cases investigated within 4 days of injury, and also that the late complication of neovascularisation, producing a serous maculopathy, may resolve and good central vision be retained without recourse to photocoagulation therapy. Patients who had visual field examinations performed within a few days of trauma were noted to have dense central scotomata, but some recovery occurred in most cases, although to a variable degree. Field defects away from fixation corresponded to an extent with areas of post-traumatic pigmentary retinopathy, but in some portions of retina with normal background appearances sensitivity was also noted to be reduced. Scotomata corresponding specifically to choroidal tears or nerve fibre bundle defects were not recorded. Improvement of visual acuity may be expected, except in cases where a choroidal tear has involved the fovea or progressive choroidal neovascularisation led to permanent macular damage.

Adolescent↗
PubMed1980

Photostress recovery times in cases of central serous retinopathy.

Photostress recovery times were measured in 50 normal individuals in the age group 20-50 years and in 27 patients who had developed central serous retinopathy. A flash generator of a commercially available fundus camera was used to provide the appropriate stimulus. The results showed that photostress recovery times were grossly abnormal in patients with central serous retinopathy for the first few weeks after the onset of symptoms, but gradually returned to normal values by 5 months and remained so thereafter. In a few patients during the recovery phase a transient paradoxical response was noted, whereby the photostress recovery times became less than in the unaffected control eye.It appears that the use of a fundus camera to provide photostress stimulus has merit because the light source is subject only to slight variation in intensity, standardization of responses is possible and the technique can be employed on patients about to have fluorescein angiographic studies for diagnostic or documentation purposes.

Adult↗
PubMed1980

Chorioretinitis sclopetaria.

Chorioretinitis sclopetaria occurs as a result of missiles penetrating into the orbit and grazing, but not perforating, the sclera. Localized destruction of both the retina and choroid develops adjacent to the impact site and these structures are subsequently replaced by a connective tissue response. Extensive damage is produced in the retinal circulation, which is not confined to the zones containing connective tissue plaques. Residual field defects are found to relate more closely to areas of retinal capillary non-filling than to the while scarred areas.

Adolescent↗
PubMed1978

Histological changes in the internal retinal layers produced by concussive injuries to the globe. An experimental study.

The level of lesions within the human retina causing transient post-concussive retinal opacification (Berlin's oedema) remains unclear, as histological examination of this tissue is rarely possible before the ophthalmoscopic changes resolve. Studies in vivo of retinae in man and experimental animals previously subjected to blunt, nonperforating mechanical injuries suggest that the development of intracellular oedema may be the principal reason why the retina becomes opaque. The retinae of experimental animals (pigs), whose eyes had been subjected to concussive injuries, were examined histologically after the removal and fixation of the globes, at periods ranging from a few minutes to 7 days after trauma. Disturbances were noted in the inner retinal layers immediately after trauma, which included transient swelling of the mitochondria in the nerve fibres lasting for only a few hours, and marked intracellular oedema of the glial elements which took 2 to 3 days to resolve.

Animals↗
PubMed1977

Operating microscope eyepiece heaters.

Precipitation of water vapour from expired air on to exposed eyepiece lenses of operating microscopes can seriously interfere with the surgeon's view. By warming these optical surfaces to temperatures well above the dew point of expired air this problem is eliminated. A pair of small heaters were designed to clamp over the eyepiece tubes of a standard operating microscope and their effectivity assessed.

Heating↗