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Biomedical subjects

J C Hill

Publications and source records attributed to J C Hill.

At least 19 recordsLinked to original sources
PubMed1999

HLA-A and -B alleles in cornea donors as risk factors for graft rejection.

We determined the human leucocyte antigen (HLA)-A, -B and -DR allele frequencies in recipients and donors of 115 cornea transplants, for recipients who developed graft rejection and those who did not. No difference in HLA allele frequencies of the recipients was found. The frequencies of the HLA-A26, -B35 and -B44 alleles in cornea donors were increased in recipients who developed graft failure. The detrimental effect on corneal graft survival of these alleles was significant (p < 0.001). No such effect was observed in renal transplantation. Corneal graft survival was similar when one or two A26, B35 or B44 alleles were present on the donor cornea. The negative effect was similar in magnitude to the previously reported negative effect of an HLA-B locus match between donor and recipient. When both a B-locus match and an A26, B35 or B44 allele were present, the negative effect on graft survival was twice as strong, indicating that different immune mechanisms are responsible for these phenomena.

Alleles↗
PubMed1998

Lower extremity purpura associated with new-onset autoimmune hepatitis: an unusual presentation.

Autoimmune hepatitis is a chronic necroinflammatory disorder of unknown cause. The morbidity and mortality of this potentially lethal disorder can be minimized by timely diagnosis and treatment. Patients can present with a wide variety of clinical and laboratory manifestations, including high titers of antinuclear antibody and other autoantibodies commonly associated with dermatologic disorders. Overt evidence of hepatic injury can be a late finding. An unusual presentation of autoimmune hepatitis and a brief review of its clinical features are presented, with an emphasis on those findings most relevant to a practicing dermatologist.

Adult↗
PubMed1997

An adverse matching effect for the HLA-B locus in corneal transplantation.

The results of tissue typing on 115 recipient/donor pairs prior to corneal grafting were analyzed with the proportional hazard regression model for the incidence of the first rejection episode and for graft failure from rejection. Like other investigators, we found that a previously failed corneal graft and the degree of recipient corneal vascularization were significant risk factor for graft rejection. ABO blood group matching had no effect. The absence of mismatches in both the HLA-A and HLA-DR loci decreased the incidence of rejection. However, no difference was observed for the presence of one versus two mismatches. Regression results for the HLA-A and DR loci were not significant. Surprisingly, matching for one or both HLA-B alleles resulted in a significantly higher incidence of graft rejection episodes (P < 0.005) and of graft failure (P < 0.052). This adverse matching effect for the B locus was proportional to the number of mismatches.

ABO Blood-Group System↗
PubMed1997

Latency of contralateral sound-evoked auditory efferent suppression of otoacoustic emissions.

The suppression of transiently evoked otoacoustic emissions by contralateral sound stimulation is thought to occur as a result of the action of the efferent pathway from the superior olivary complex to the cochlea via the medial olivo-cochlear neurons. The purpose of this study was to determine the time taken for this pathway to activate the suppressive mechanism in response to contralateral sound in normal human subjects. The time for onset of suppression was found to be between 7 and 20 ms.

Acoustic Stimulation↗
PubMed1996

Does post-laparoscopy pain relate to residual carbon dioxide?

We studied 20 day case gynaecological laparoscopy patients, who had an erect chest X ray taken before discharge. Patients were telephoned the next day for a semi-structured interview. Particular note was made of shoulder tip pain and pain relieved by changing posture. The X ray was analysed for measurements of the length of arc and height of the gas bubble under each hemi-diaphragm, from which an estimation of bubble volume was also made. We found statistically significant correlations between both the length of arc (p = 0.005) and volume of gas bubble (p = 0.008) on the right side, with the pain score. Residual gas can be a prominent cause of post-laparoscopy pain.

Carbon Dioxide↗
PubMed1996

Age-dependent decline of attention deficit hyperactivity disorder.

OBJECTIVE: This study was undertaken to assess whether the diagnosis of attention deficit hyperactivity disorder (ADHD) is retained from childhood into adulthood. METHOD: A search of the literature yielded nine prospective studies in which cohorts of children with the disorder were formed and then reexamined 4-16 years later to determine the level of retained ADHD. The resulting data were subjected to nonlinear regression analysis to ascertain the relationship with chronological age. RESULTS: The data followed an exponential decline over time to a high degree of accuracy. CONCLUSIONS: The rate of ADHD in a given age group appears to decline by 50% approximately every 5 years. If a prevalence of ADHD in childhood of 4% is assumed and the exponential decline extrapolated, the estimated rate of adult ADHD ranges from about 0.8% at age 20 to 0.05% at age 40.

Adolescent↗
PubMed1996

The relative importance of risk factors used to define high-risk keratoplasty.

The risk factors commonly used to classify high-risk keratoplasty were studied to determine their relative importance. Survival analysis of a single-surgeon series of 702 grafts was performed using both univariate and multivariate analysis, with graft failure from rejection being the end point. The number of previously rejected grafts, the number of vascularized recipient corneal quadrants, the number of recipient stromal vessels, and the original diagnosis were highly significant factors for survival (P = 0.0001). Diseases usually associated with avascular corneas, such as keratoconus, fared best, whereas diseases causing vascularization had a poor diagnosis. Old interstitial keratitis had a good prognosis, indicating that ghost vessels are not a risk factor. Although a previously rejected graft was a significant risk factor, this was only true in vascularized recipients. There was no significant difference in survival between repeat grafts into avascular corneas and first-time grafts into avascular corneas, indicating that it is the vascularization associated with rejection that confers the increased risk. Multivariate analysis indicated that the number of vascularized quadrants (P = < 0.0001), the number of vessels (P = < 0.0001), and a previously rejected graft (P = 0.0002) were risk factors for graft survival but that patient age was not a significant risk factor (P = 0.9). Three distinct survival groupings were evident, namely, avascular corneas, corneas with 1-2 quadrants or 1-15 vessels, and corneas with 3+ quadrants of vascularization or 16+ vessels. This would seem a reasonable basis for classifying recipient corneas into low-, intermediate- and high-risk cases.

Analysis of Variance↗
PubMed1995

Immunosuppression in corneal transplantation.

This paper reviews the clinical post-operative management of keratoplasty and the management of corneal graft rejection. In both instances corticosteroids remain the mainstay of treatment; however, the literature shows a wide range for both route and frequency of administration. Grafts at 'high risk' require more immunosuppressive therapy, but no universally accepted definition of high risk exists and consequently different treatment regimens are difficult to compare and evaluate. Studies using univariate and multivariate survival analysis suggest that recipient corneas can be divided into low, medium and high risk depending on the number of quadrants of vascularisation (avascular, 1-2 quadrants and 3+ quadrants respectively). This wider classification would make the devising and comparing of treatment regimens more consistent. In high-risk cases, corticosteroids alone provide insufficient immunosuppression and systemic cyclosporine is needed in exceptional cases. When managing rejection episodes, a severe reaction involving the endothelium often does not respond to topical steroids alone, and systemic corticosteroids are required. Instead of oral steroids, we now prefer to use an intravenous 'pulse' of 500 mg methylprednisolone: this is at least as effective, avoids prolonged medication, and may confer some long-term benefit.

Administration, Topical↗
PubMed1995

Systemic cyclosporine in high-risk keratoplasty: long-term results.

Systemic cyclosporine (CSA) was given to 43 high-risk keratoplasty patients (vascularisation in three or four quadrants and > 16 stromal vessels): 14 received CSA for 12 months (long CSA group) and 29 for a 4-6 month period (short CSA group). A group of 37 similar high-risk keratoplasty patients received no CSA (no CSA group). In the no CSA group 27 (73%) grafts had rejection episodes compared with 21 (48.8%) in the combined CSA group (p = 0.025). Rejection was reversed in only 23.3% of the no CSA group, compared with 50% and 87.5% in the short (p = 0.06) and long (p = 0.002) CSA groups respectively. Compared with the no CSA group, overall graft survival was better in both the short (p = 0.019) and long (p = 0.0056) CSA groups. This improvement resulted from both a reduction in the incidence, and an increase in the reversal rate, of rejection episodes. The improvement continued after stopping CSA, suggesting that some immunological privilege had been re-established. Acuities of 20/40 or better were achieved by 44.8% and 50% of eyes in the short and long CSA groups respectively, compared with 13.5% of eyes in the no CSA group.

Adolescent↗
PubMed1995

Contact urticaria to the M17 protective mask.

A case of contact urticaria to a compound used in the production of the M17 protective mask is reported. The new M40/42 series protective mask has a different composition, and should be tried as an alternative to the M17 mask in service members with black rubber allergies.

Adult↗
PubMed1995

Bilateral linear corneal ectasia. An unusual case and its surgical management.

A 24-year-old man presented with narrow, linear areas of thinning situated horizontally in the upper part of both corneas. These areas were associated with progressive corneal ectasia, causing high degrees of "against the rule" astigmatism. By excising the affected areas, the refractive error was significantly improved in both eyes. Features of the disease suggested that the condition was related to the other ectatic corneal dystrophies.

Adult↗
PubMed1994

HPLC purification and separation of 5,5'-substituted-2,4-imidazolidinedithiones.

Several 5,5'-substituted-2,4-imidazolidinedithiones, synthesized from aldehydes or ketones, have been purified by HPLC using poly(styrene-divinylbenzene) packings. Purified 5,5'-substituted-2,4-imidazolidinedithiones have been identified in column effluent by UV absorbance and corroborated by mass spectrometry. Several silica-based, polymeric, and poly(styrene-divinylbenzene)-based packings were evaluated as matrices for resolution of a mixture of purified 5,5'-substituted-2,4-imidazolidinedithiones.

Chromatography, High Pressure Liquid↗
PubMed1994

Systemic cyclosporine in high-risk keratoplasty. Short- versus long-term therapy.

BACKGROUND: In high-risk keratoplasty, the failure rate from rejection is high, especially in the early postoperative period. If rejection could be prevented during this period, then ultimately a degree of immunologic privilege may be re-established, resulting in long-term graft survival. Cyclosporine (CSA) given systemically prevents graft rejection, but because of the potential side effects and cost, the duration of treatment is an important factor. The author examines the effectiveness of short- and long-term CSA regimens in preventing irreversible graft rejection. METHODS: Forty-three patients with high-risk corneas (vascularization in 3 or 4 quadrants and > 16 stromal vessels) received corneal grafts and systemic CSA. Fourteen patients received the drug for 12 months and 29 for a shorter period of 4 to 6 months. A similar high-risk group of 37 patients received no systemic medication. RESULTS: In the control group, 23 grafts (62.2%) irreversibly rejected, compared with 9 (31.0%) and 1 (7.1%) in the short- and long-term CSA groups, respectively. The grafts of patients receiving CSA had a significantly better survival rate (P = 0.0005) than those in the control group. If time of CSA treatment also was considered, significance increased (P = 0.00008). CONCLUSIONS: Systemic CSA significantly reduces failure from irreversible rejection in high-risk keratoplasty, but for maximal effect, a 12-month period of treatment is necessary.

Administration, Oral↗
PubMed1994

Mixed lymphocyte culture responses in rabbits undergoing corneal grafting and topical cyclosporine treatment.

Using a vascularized cornea rabbit model closely resembling human high-risk keratoplasty, corneal allografts were performed on three groups of animals that were paired and tested preoperatively by mixed lymphocyte cultures (MLCs). The three groups were group A, unmodified controls with clear corneas; group B, untreated animals with vascularized corneas; and group C, animals treated with topical cyclosporine (CSA) with vascularized corneas. The MLC results were expressed as stimulation indices (SIs) and divided into low (SI < or = 20) and high (SI > 20) responders and were correlated with final outcome of grafts using survival analysis estimates. In group A, five of 13 (38.5%) grafts rejected, the chance of failure depending on the degree of MLC mismatch between donor and recipient (p = 0.02). All allografts in group B rejected regardless of the degree of mismatch. In group C, seven of 12 (58.3%) grafts rejected, indicating that topical CSA significantly improved survival (p = 0.003) compared with group B. Grafts with mild degrees of MLC mismatch (low responders) survived better (p = 0.0003) than did higher degrees of MLC mismatch (high responders), all of which rejected despite treatment. Our results indicate that both corneal vascularization and the degree of donor-recipient matching play important roles in determining corneal graft survival.

Administration, Topical↗