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Biomedical subjects

C B James

Publications and source records attributed to C B James.

14 recordsLinked to original sources
PubMed1994

Effect of trabeculectomy on pulsatile ocular blood flow.

Trabeculectomy, despite producing an effective reduction in intraocular pressure, may not prevent continued visual field loss. This may be because of the presence of other factors in the pathogenesis of glaucoma. Vascular factors have been suggested as being particularly important. To study the effect of trabeculectomy on ocular blood flow the technique of ocular pulse analysis has been used to derive a measure of pulsatile ocular blood flow in 17 patients (average age 65.6 (SD 1.8) years) undergoing trabeculectomy. A significant increase in pulsatile ocular blood flow of 29% was observed in the group as a whole in the standing position following operation but in some individuals blood flow changed only slightly despite a large reduction in intraocular pressure. The significance of these findings in relation to the prognosis of visual field preservation following trabeculectomy is discussed.

Aged↗
PubMed1993

Urban violence in Los Angeles in the aftermath of the riots. A perspective from health care professionals, with implications for social reconstruction.

Beginning April 29, 1992, Los Angeles, Calif, was engulfed in a 3-day insurrection reflecting the residents' responses to a legal ruling. Unlike the media-painted picture, this article argues that the enormous outburst of violence and consequential property destruction was not the exclusive domain of the citizens of South-Central Los Angeles and that available data will not support the maintenance of the prevailing uneven distribution of civic and state resources in health care, educational programs, and economic opportunities. What it does support is the proposal for a more equitable allocation of resources among institutions, groups, and peoples, complemented by community empowerment, a more civic-oriented police operation, and a more rational approach to social reconstruction in which all elements of the society are full participants. Finally, the article suggests that augmentation of the present "law and order" approach and the paramilitary police already have proven economically ineffective. Given the dominant role of the medical profession in social and civic life, it is now appropriate for the medical profession to enter the debate on policies of health improvement, violence deterrence, and the general field of social reconstruction.

Health Occupations↗
PubMed1992

Activation of protein kinase C inhibits adenovirus VA gene transcription in vitro.

We report here that activation of protein kinase C (PKC) results in the inhibition of adenovirus virus-associated (VA) gene transcription in vitro. The involvement of PKC in this inhibition is supported by the fact that the addition of PKC inhibitors to transcription reactions in which the PKC cofactor phosphatidyl serine (PS) was present resulted in increased levels of transcription compared to those in reactions in which PKC activity was stimulated in the absence of PKC inhibitors. Furthermore, based on these in vitro studies we propose that the inhibition of VA gene transcription is possibly due to the inability of the VA gene to form an active transcription complex following the activation of PKC. This conclusion was drawn from in vitro data which demonstrated that PS stimulation of endogenous PKC present in cell extracts resulted in failure to isolate a fully initiated, stable transcription complex.

Adenoviruses, Human↗
PubMed1992

Acceleration of adenovirus replication and increased virion production by treatment with the steroid hormone 17 beta-estradiol.

We report here that concentration of an estrogen known to promote enhanced transformation and to increase oncogenicity of rat embryo cells, accelerate the production and increase the yield of progeny virions in adenovirus type 12 (Ad 12)-infected HEp-2 cells. Further, measurement of the incorporation of radioactive RNA and DNA precursors indicated that macromolecular synthesis in the estrogen-treated, infected cells was accelerated. Possible explanations for this observation are discussed.

Adenoviridae↗
PubMed1991

Factors influencing the ocular pulse--axial length.

The amplitude of the intraocular pressure pulse and pulsatile ocular blood flow (POBF) were correlated with the axial length and refraction of 68 eyes of healthy subjects. Measurements were obtained with subjects in the sitting position using an ophthalmic A-scan and a pneumotonometer linked to a Langham ocular blood-flow system. The amplitude of the ocular pulse and the magnitude of POBF were found to decrease with increasing axial length (r = -0.61, P less than 0.001 and r = -0.74, P less than 0.001, respectively). A similar close relationship was found between the ocular pulse amplitude and POBF and the refractive state of the eye (r = 0.63, P less than 0.001 and r = 0.7, P less than 0.001, respectively). The reasons for the association are discussed and the importance of the observations in the construction of studies in which ocular pulse amplitude or POBF are to be measured in different groups of subjects is emphasised.

Adolescent↗
PubMed1991

Factors influencing the ocular pulse--the heart rate.

Using pneumotonometry combined with a Langham ocular blood-flow system, measurements of pulsatile ocular blood flow (POBF) were performed in eight ocular normotensive patients with implanted cardiac pacemakers, with the subjects assuming both the erect and the supine postures. Sequential measurements of POBF were made at pre-set values of heart rate over the physiological range between 60 and 120 beats/min at intervals of 10 beats/min. With patients in the supine position, measurements of cardiac output and stroke volume indices were also recorded by impedance cardiography. The mean pulse amplitude of the intraocular pressure (the ocular pulse) decreased as heart rate increased, and this change was statistically significant in both postures according to repeated-measures analysis of variance (erect: f = 18.7, P less than 0.0001; supine: f = 18.8, P less than 0.0001). As measured in supine patients following an increase in heart rate, the pulse amplitude decreased in parallel with a decline in stroke volume index (f = 18.8, P less than 0.0001). Up to a level of 90 beats/min, the mean POBF increased with heart rate, but it declined above this rate in both erect and supine postures. At all heart rates, intraocular pressure was higher when subjects were supine than when they stood erect (f = 4.3, P less than 0.001). At lower heart rates of 70 and 80 beats/min, ocular pulse volume and POBF were significantly lower in supine patients than in erect subjects (70 beats/min: t = 3.89, P less than 0.01 vs; t = 3.87, P less than 0.01; 80 beats/min: t = 2.85, P less than 0.05 vs; t = 2.87, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

The effect of posture on the intraocular pressure and pulsatile ocular blood flow in patients with non-arteritic anterior ischaemic optic neuropathy.

Intraocular pressure (IOP) and pulsatile ocular bloodflow (POBF) have been recorded in 15 patients with unilateral non-arteritic anterior ischaemic optic neuropathy (na-AION) and in 28 healthy subjects of comparable age. Measurements were obtained in both the upright and lying postures with a pneumotonometer linked to a Langham ocular bloodflow system. By comparison with the healthy subjects, patients with na-AION were found to have a significantly greater postural pressure change in IOP (3.9 +/- 0.4 mmHg in the affected eye and 3.6 +/- 0.6 mmHg in the unaffected eye of the patients with na-AION compared to 2.2 +/- 0.4 mmHg in the right eye of the healthy subjects P less than 0.01 and less than 0.05 respectively). There was no significant difference between the IOP in the affected and unaffected eyes of patients with na-AION nor between this group and the healthy subjects in either posture. Pulsatile ocular bloodflow measurements were similar in both groups and in both eyes of the patients with na-AION. In both groups POBF fell significantly on lying down (healthy right eyes -84 +/- 16 ul/min p less than 0.01, na-AION affected eye -84 +/- 24 ul/min p less than 0.01, unaffected eye -83 +/- 26 ul/min p less than 0.001). These figures represent decrements of 19% in all groups. These findings suggest that assumption of the supine posture may be associated with a reduction in the pulsatile component of ocular perfusion. The importance of this in the pathogenesis of na-AION is discussed.

Adult↗
PubMed1991

Pulsatile ocular blood flow in patients with low tension glaucoma.

Measurements of the intraocular pressure (IOP) pulse and pulsatile ocular blood flow (POBF) have been made in 22 patients with bilateral low tension glaucoma (LTG) and 29 healthy subjects matched as closely as possible for age, refractive error, IOP, systemic pulse pressure, and heart rate. Recordings were made in both the standing and supine positions. The amplitude of the intraocular pressure pulse was significantly lower in patients with LTG (1.2, SEM 0.1 mmHg standing, and 1.3, SEM 0.1 mmHg lying) than in healthy subjects (1.9, SEM 0.1 mmHg standing, and 2.0 SEM 0.1 mmHg lying): p less than 0.001 standing and p less than 0.002 lying. Measurement of POBF also showed a significant reduction between the healthy subjects (428 (31) SEM microliters/min standing and 345 (28) SEM microliters/min lying) and subjects with LTG (301 (27) SEM microliters/min standing and 249 (24) SEM microliters/min lying), p less than 0.005 standing and p less than 0.02 lying. This represents a difference of approximately 30% between the two groups in either posture. A close non-parametric correlation existed between the level of IOP and the POBF (r = 0.75, p less than 0.001 standing, and r = -0.55, p less than 0.02 lying). Such a correlation was not present in the healthy subjects. A reduction in POBF occurred in both groups on assuming the supine posture (healthy subjects 83 (16) SEM microliters/min, LTG subjects 52 (17) SEM microliters/min). These figures represent reductions of 19% and 17% respectively in comparison with the standing value. The results lend further confirmation to the hypothesis that vascular factors are associated with low tension glaucoma.

Adult↗
PubMed1990

Night myopia.

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Accidents, Traffic↗
PubMed1990

The natural history of non-arteritic anterior ischaemic optic neuropathy.

Seventy one patients with non-arteritic anterior ischaemic optic neuropathy were studied retrospectively. Sixty three (89%) were followed to the end of the study or death, mean follow up time was 5.3 years. Whilst twenty (28%) had diabetes or hypertension, in thirty nine (55%) no predisposing condition was identified. In those who had monocular disease at presentation (68), subsequent involvement of the second eye occurred in seventeen (25%), seven within the first year. Nineteen patients died within the study period. Of these, nine died from myocardial infarction and four from cerebrovascular disease. This is a significant increase above figures calculated from the Office of Population Census and Surveys (p less than 0.001 for all causes, p less than 0.002 for myocardial infarction and cerebrovascular disease). Such an increase in mortality has not been previously reported, and implies that this condition carries a more sinister systemic prognosis than is frequently supposed.

Adult↗
PubMed1988

DNA-stimulated protein phosphorylation in HeLa whole cell and nuclear extracts.

Incorporation of 32P from gamma-labeled ATP into a number of polypeptides in HeLa whole cell and nuclear extracts was dependent on added double-stranded DNA or poly(dI-dC), but not denatured or supercoiled DNA. DNA-dependent phosphorylation of a high Mr endogenous substrate could be reconstituted from the precipitate formed after incubation of whole cell extracts with DNA. Fractionation of extracts by phosphocellulose or DEAE-Sephacel chromatography yielded preparations that phosphorylated casein as well as endogenous polypeptides in a DNA-dependent manner. These results are consistent with the existence of a novel protein kinase in HeLa cells that is highly dependent upon the presence of double-stranded DNA for efficient phosphorylation of a variety of substrates.

Adenosine Triphosphate↗
PubMed1988

Infectious crystalline keratopathy.

We present a patient who developed a crystalline keratopathy after a penetrating keratoplasty. This rare complication can be caused by bacterial infection, and the patient responded to the appropriate antibiotic therapy. The literature is reviewed and possible causes and mechanisms of the crystalline appearance are discussed.

Adult↗