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Biomedical subjects

J R Ross

Publications and source records attributed to J R Ross.

At least 55 records · Page 3Linked to original sources
PubMed1993

Characteristics of corneal xenograft rejection in a discordant species combination.

PURPOSE: To characterize the fate of Lewis rat corneas transplanted to Hartley guinea pigs. METHODS: Full-thickness Lewis rat corneal buttons were grafted orthotopically to Hartley guinea pigs (xenografts), ACI rats (allografts), or Lewis rats (isografts). Two panels of recipients were presensitized with xenogeneic skin grafts or allogeneic skin grafts. Serum samples were collected pre- and post-transplant and analyzed by flow cytometry and indirect immunofluorescence. RESULTS: Unlike vascularized xenografts that reject within 30 min, corneal xenografts had a mean survival time of 8 days. Presensitization with guinea pig skin grafts increased recipient IgM and IgG xenoantibody levels, as measured by flow cytometry on guinea pig hematopoietic cells, and significantly accelerated corneal xenograft rejection with a mean survival time of 5 days. Presensitization with allogeneic ACI skin grafts had no effect on xenoantibody levels or xenogeneic corneal graft survival. Guinea pig corneas stained by indirect immunofluorescence with normal rat serum exhibited low (1+) but significant binding of IgG and IgM, primarily on epithelium and stroma. Serum from Lewis rats that rejected a corneal xenograft had elevated IgG and IgM xenoantibodies that reacted strongly (4+) with guinea pig cornea and heart. CONCLUSIONS: In the discordant guinea pig-to-rat species combination, donor corneas express xenoantigens; rejection of corneal xenografts stimulates IgM and IgG xenoantibody production; sensitization to xenoantigens can accelerate corneal xenograft rejection; and discordant corneal xenografts, unlike vascularized organs, are not hyperacutely rejected.

Acute Disease↗
PubMed1992

Effect of donor Langerhans cells on corneal graft rejection.

Unlike other cutaneous surfaces, the central portion of the corneal epithelium is typically devoid of Langerhans cells. The absence of Ia+ Langerhans cells in the central cornea is of more than casual interest and may explain the immunologic privilege that is characteristic of corneal allografts. The present communication summarizes previous studies that examined the role of corneal Langerhans cells in eliciting alloimmune responses and corneal graft rejection in rodents. Under normal circumstances, corneal allografts are poorly immunogenic when residing in the avascular ocular graft bed even though the graft displays large quantities of alloantigens. The afferent blockade of the immune response can be circumvented by donor-derived Langerhans cells that serve as potent immunogens for all categories of corneal allografts except grafts involving allodisparity only at class I major histocompatibility complex loci. Thus, the presence of donor-derived Langerhans cells exerts profound effects on the fate of corneal allografts.

Corneal Transplantation↗
PubMed1991

Paleozoic Foraminifera.

The approximately 300 million years that make up Paleozoic time saw the evolution of eight of the fifteen recognized suborders of Foraminifera. Of the suborders present in the Paleozoic, seven are morphologically relatively simple, slowly evolving, and continued into Mesozoic and Cenozoic times to become the ancestoral lineages from which evolved several additional post-Paleozoic suborders. In contrast, an eighth Paleozoic suborder, the Fusulinina, was an abundant, ecologically dominant group that evolved from simple to highly specialized forms and had a history of rapid evolution with diverse lineages. Fusulinines became extinct at the end of the Paleozoic. Their early representatives may have given rise to three and eventually four post-Paleozoic suborders. A number of suborders in the Paleozoic have similar, supposedly independent, early evolutionary patterns with the following series of morphological steps: (1) single chambers with or without apertures depending on the amount of wall cement; (2) groups of chambers that appear to be buds or aggregations of individuals rather than true chambers; (3) a proloculus followed by a tubular second chamber that is first erect and gradually evolves into enrolled free-living individuals; (4) development of constrictions in the tubular chamber; and finally (5) evolution of true chambers. These morphological steps, which are basic organizational steps with evolutionary significance, appear in lineages with quite different test compositions and, therefore, are considered only distantly related in the present classification.

Animals↗
PubMed1991

Budesonide once-daily in seasonal allergic rhinitis.

A randomized, parallel group, double-blind multi-centre study was carried out in 342 patients with symptomatic seasonal allergic rhinitis to assess the efficacy and tolerability of intranasal budesonide administered either as a single morning dose of 400 micrograms or as a 200 micrograms twice-daily dose, morning and evening, for 4 weeks. Both treatments improved the symptoms of seasonal allergic rhinitis; specific nasal symptom scores recorded daily by the patient being reduced. The proportions of patients symptom free after 4-weeks' treatment were 46% in the 400 micrograms once-daily group and 54% in the 200 micrograms twice-daily group, with total daily symptom scores recorded by diary cards reduced by 79% and 80%, respectively. The differences between the groups were not statistically significant. Sub-group analysis of patients allergic to grass pollen (n = 166) showed similar total symptom scores at each level of grass pollen exposure (no significant difference between treatment groups). Patients assessed both treatments to be effective (no significant difference between groups), with 65% of patients questioned stating a preference for a once-daily treatment given equal symptom control. Both treatments were equally well tolerated and few side-effects were reported.

Administration, Intranasal↗
PubMed1991

Intranasal budesonide once daily in seasonal allergic rhinitis.

A double-blind, parallel-group, multi-centre study was carried out in 248 patients with symptomatic seasonal allergic rhinitis to assess the effectiveness and tolerability of intranasal aqueous budesonide given as a single daily dose each morning of 400 micrograms compared with the conventional dosage regimen of 200 micrograms twice daily. After a 1-week run-in period during which only oral terfenadine was allowed for intolerable symptom relief, symptomatic patients were allocated at random to receive budesonide in one or other dosage regimen for 3 weeks. The results of assessments made by the physician at clinic visits and by patients recording daily data on diary record cards showed that specific nasal symptom incidence and severity were significantly (p less than 0.001) reduced in both treatment groups. The proportions of patients symptom-free at 3 weeks were 40% in the 400 micrograms once daily and 45% in the 200 micrograms twice daily group; in addition, mean nasal symptom scores from the daily diary cards were significantly (p less than 0.001) reduced in both groups, with a reduction in total symptom scores of 53% and 60%, respectively. The differences between the groups were not statistically significant. Total symptom scores were significantly (p less than 0.01) reduced in both dosage groups at all levels of pollen exposure. Patients rated treatment overall as being highly effective, mean scores being very similar in both groups, and tolerability was similar and good whether budesonide was given as a 400 micrograms once daily dose or as 200 micrograms twice daily. Assuming equal symptom control, 74% of patients stated they would prefer once daily to twice daily treatment.

Administration, Intranasal↗
PubMed1990

Prevention of the induction of allospecific cytotoxic T lymphocyte and delayed-type hypersensitivity responses by ultraviolet irradiation of corneal allografts.

The effect of ultraviolet radiation (UVR) on the immunogenicity of corneal allografts was examined in a mouse model. Corneal allografts differing from the host at the entire MHC and multiple minor H loci were subjected to 200 mJ/cm2 of UVB irradiation immediately prior to heterotropic transplantation. Analysis of cytotoxic T lymphocyte and delayed-type hypersensitivity responses revealed that UVR treated corneal grafts failed to induce either CTL or DTH responses in C57BL/6 recipients. UVB treatment abolished the immunogenicity of highly immunogenic corneal grafts containing either resident or infiltrating donor-specific Langerhans cells. Sequential grafting experiments demonstrated that UVB-treated grafts rendered the hosts anergic to subsequent immunization with highly immunogenic corneal limbus grafts that contained dense concentrations of Ia+ Langerhans cells of donor origin. The results indicate that UV treatment not only reduces the immunogenicity of the corneal allograft but may also render it tolerogenic.

Animals↗
PubMed1990

Effects of in vivo and in vitro treatment with L-carnitine on isolated hearts from chronically diabetic rats.

The effects of in vivo and in vitro L-carnitine administration on cardiac function were studied in isolated perfused working hearts from control and diabetic rats. Injection of L-carnitine (3 g.kg-1.day-1, i.p.) for 2 weeks into rats previously diabetic for 6 weeks partially reversed the adverse effects of chronic diabetes on heart function. In a second experiment, a lower dose of L-carnitine (0.5 g.kg-1.day-1, i.p.) injected for 6 weeks prevented the onset of heart dysfunction in chronically diabetic rats. The protective action of L-carnitine in the myocardium appeared to be independent of any direct pharmacological effects. In both studies, L-carnitine was a potent lipid-lowering agent. The data suggests that L-carnitine administration at either dose had a protective effect against myocardial damage seen during diabetes. The mechanism(s) underlying these effects remains to be elucidated but are discussed.

Adipose Tissue↗
PubMed1990

Veneered osseous graft. Case report and technique.

Attempts to develop a predictable method of osseous regeneration evolved into the veneered osseous graft. The author has taken advantage of and incorporated several different aspects of regenerative periodontal therapy. Having treated several hundred cases with good to excellent results, success is directly related to meticulous detail. Flap design, root surface preparation, bony wall therapy and graft placement are all equally important in predicting success. By introducing into a clean bone cavity against a clean root an osteogenic base material protected by a veneer to prevent down growth of epithelium one can expect improvement of an osseous lesion. This one-step procedure is a cost effective answer to the two-step procedure. Osseous grafting with a variety of materials has become an established part of regenerative periodontal therapy. Most reports comparing grafting to surgical debridement has demonstrated an advantage with grafting no matter what the material. Successful osseous grafting does require a biologically compatible material, preferably with osteogenic potential, which would prevent a down growth of epithelium until the graft has established a "home." Equally important is site preparation. Most reports in the literature describe site preparation as "thorough root planing." This description is inadequate as actual procedures can vary widely. Specifics are missing so duplication is difficult. Chemical root conditioning was introduced as an adjunct to effective root preparation. The frequency of osseous graft success began to improve with the addition of citric acid conditioning to very mechanical root preparation regardless of the grafting material used. The development of the veneered osseous graft technique over the years has taken advantage of and incorporated several different aspects of regenerative therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Transplantation↗
PubMed1989

A dose-finding, placebo-controlled study on extended-release felodipine once daily in treatment of hypertension.

Hypertensive patients received a beta-blocker plus placebo once daily for 4 weeks. If their diastolic blood pressure (DBP) was then 95-115 mm Hg, they were randomized to receive, in addition to the beta-blocker, placebo (n = 36), felodipine-extended release (ER) 10 mg (n = 36), or felodipine-ER 20 mg (n = 37) in a 4-week double-blind parallel-group trial. All medication was administered once daily and, when BP was measured 24 h after the last dose, felodipine-ER 10 mg reduced DBP by 14 +/- 9 mm Hg (mean +/- SD) from a mean of 103 mm Hg and felodipine-ER 20 mg reduced DBP by 18 +/- 9 mm Gg from 101 mm Hg. The reductions in DBP with both doses of felodipine were greater than reductions with placebo (5 +/- 8 mm Hg, from 102 mm Hg--both p less than 0.001). At the end of the study, 21% of patients receiving placebo had a DBP less than or equal to 90 mm Hg. In contrast, 69% of patients receiving felodipine-ER 10 mg and 82% receiving 20 mg attained this level. More than 90% of patients receiving 10 mg felodipine-ER once daily had a reduction in DBP greater than 5 mm Hg 24 h postdose. Felodipine-ER was well tolerated. Felodipine-ER once daily is an effective antihypertensive drug for patients who require therapy in addition to a beta-blocker; the tolerability in this study was good, and a starting dose greater than 10 mg once daily is not indicated.

Adult↗
PubMed1989

Catheter drainage of the pericardium: its safety and efficacy.

A retrospective chart review identified 46 consecutive patients who underwent catheter drainage of the pericardium over 3 years. Cardiac tamponade was present in the majority of patients, and the underlying cause was tumour metastasis in 72%. Pericardial catheterization was accomplished by the Seldinger technique using the subxiphoid approach. Catheter insertion was successful in 42 of the 46 patients, and in only 1 was there a serious complication. The mean duration of catheter drainage was 3 days. The pericardial space was successfully drained in all but one patient, who subsequently required surgery. Intrapericardial chemotherapy was administered in 27 patients. There was no instance of catheter-associated sepsis. Supraventricular arrhythmias occurred in 19% of patients, but all were managed medically. There were no late complications attributable to the period of drainage. The authors conclude that catheter drainage of the pericardium is a safe and effective means of providing definitive drainage of the pericardial space.

Cardiac Tamponade↗
PubMed1988

A comparison of felodipine and propranolol as additions to hydrochlorothiazide in the treatment of hypertension.

Eighty one patients with uncomplicated hypertension who required additional antihypertensive medication (diastolic Phase V [dBP] greater than or equal to 95 mm Hg) after 4 weeks treatment with hydrochlorothiazide (HCTZ) 25 mg o.m. were randomized to receive felodipine 5 mg b.i.d. (n = 40) or propranolol (n = 41) 80 mg b.i.d. in addition to HCTZ 25 mg o.m. If the dBP measured about 12 h post-dose was not less than or equal to 90 mm Hg after 4 weeks, the dose of felodipine or propranolol was doubled. The double blind trial period was 8 weeks for all patients. Over the 8 week period, felodipine reduced the seated dBP from 100 to 83 mm Hg and propranolol from 101 to 86 mm Hg. The attained seated dBPs were significantly different in the two groups. About one third of patients in each group received the high dose of second-line therapy. After 8 weeks 91% of patients receiving HCTZ+felodipine and 84% receiving HCTZ+propranolol had a dBP less than or equal to 90 mm Hg. Both regimens were well-tolerated with an equal incidence but different pattern of adverse events (felodipine: flushing, headache and peripheral oedema; propranolol: dyspepsia, fatigue and vasospasm). In this 8-week study, felodipine and propranolol were safe and effective second-line antihypertensive drugs when added to hydrochlorothiazide. At the doses selected, felodipine was at least as effective as propranolol.

Adult↗