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Biomedical subjects

M A Lloyd

Publications and source records attributed to M A Lloyd.

At least 37 records · Page 2Linked to original sources
PubMed1994

Intermediate-term results of a randomized clinical trial of the 350- versus the 500-mm2 Baerveldt implant.

BACKGROUND: The Baerveldt glaucoma implant is a large equatorial aqueous shunting device that is installed through a single-quadrant conjunctival incision. The intermediate-term results of a randomized study comparing the 350- and 500-mm2 Baerveldt implants are reported. METHODS: Seventy-three patients with medically uncontrollable, nonneovascular glaucomas associated with aphakia, pseudophakia, or failed filters were enrolled in a randomized, prospective study comparing 350- and 500-mm2 Baerveldt implants. Surgical success was defined as 6 mmHg < or = final intraocular pressure < or = 21 mmHg without glaucoma reoperation or devastating complication. RESULTS: Of patients with 350- and 500-mm2 implants, 93% and 88%, respectively, achieved surgical success (18-month life-table analysis, P = 0.93). The 500-mm2 implants afforded intraocular pressure control with significantly fewer medications (0.7 versus 1.3; P = 0.006). The postoperative visual acuities remained within one line of the preoperative visual acuities or improved in 62% and 66% of patients in the 350- and 500-mm2 groups, respectively (P = 0.93). Complication rates were statistically similar. The most frequent ones in the 350- and 500-mm2 groups, respectively, were serous choroidal effusion (16% and 32%), strabismus (16% and 19%), anterior uveitis (14% and 11%), and corneal or corneal graft edema (11% each). CONCLUSION: The intermediate-term results of the 350- and 500-mm2 Baerveldt implants were statistically comparable with respect to surgical and visual outcomes, as well as complications, although the larger implant was associated with a higher rate of some complications. However, the 500-mm2 Baerveldt implant afforded intraocular pressure control with fewer medications than the 350-mm2 implant.

Adolescent↗
PubMed1994

Rhegmatogenous retinal detachment after Molteno glaucoma implant surgery.

BACKGROUND: The Molteno implant is a device used for surgical treatment of complicated glaucoma. Rhegmatogenous retinal detachment (RD) is a relatively rare complication of Molteno implant surgery. This study was undertaken to evaluate the clinical features including the surgical management and postoperative outcome of patients with rhegmatogenous RD after Molteno implant surgery. METHODS: The authors reviewed 350 consecutive patients who had Molteno surgery and identified 16 patients with subsequent rhegmatogenous RD. They also studied one patient referred for RD repair after Molteno surgery at another institution. RESULTS: The risk of rhegmatogenous RD was 5%. Seventy percent (12/17) of the patients presented within 4 months of the Molteno procedure. Dialysis and flap tear were the most common types of retinal break found. Forty-one percent (7/17) of the patients had proliferative vitreoretinopathy. In three patients, clinical features suggested RD resulting from the Molteno procedure. In other patients, previous ocular surgery and underlying ocular disease may have contributed to the development of RD. Retinal detachment repair was attempted in all patients. Among 16 patients with at least 6 months of follow-up, 56% (9/16) had successful retina attachment. Forty-four percent (7/16) of the patients maintained formed vision. Eighteen percent (3/16) of the patients maintained visual acuity of at least 20/40. Intractable glaucoma did not develop in any of the patients with an attached retina. Recurrent RD, endophthalmitis, cyclitic membrane, or intractable glaucoma led to phthisis bulbi or enucleation in 44% (7/16) of the patients. CONCLUSION: A combined approach by vitreoretinal and glaucoma surgeons can restore vision and maintain glaucoma control in patients with rhegmatogenous RD associated with Molteno implant surgery.

Adolescent↗
PubMed1994

Initial clinical experience with the baerveldt implant in complicated glaucomas.

BACKGROUND: The Baerveldt glaucoma implant is an aqueous shunting device with a large surface area that is installed through a conjunctival incision in one quadrant of the eye. This study presents the initial results of the first 13 patients who underwent Baerveldt implantation as part of the Food and Drug Administration approval process. METHODS: Thirteen patients with medically uncontrollable complicated glaucomas underwent one-stage implantation of either a 200- or 350-mm2 Baerveldt implant without postoperative systemic antifibrosis therapy. Surgical success was defined as intraocular pressure greater than or equal to 6 and less than or equal to 21 mmHg without glaucoma reoperation or devastating complication. RESULTS: Eight patients (62%) had successful surgical outcomes, with a mean follow-up of 17.3 +/- 7.0 months (+/- standard deviation) (range, 6-24 months). Seven (70%) of the ten patients with glaucomas associated with aphakia or pseudophakia had successful outcomes, whereas only one (50%) of the two patients with neovascular glaucomas had a successful outcome. One patient with glaucoma associated with nanophthalmos and an unsuccessful filtering procedure had a failed outcome. The postoperative visual acuities remained within one line of the preoperative visual acuities or improved in 62% of the patients. The most frequent complications among all patients were transient serous choroidal effusion (23%) and hyphema (15%). CONCLUSION: Initial results of the Baerveldt implant generally are comparable with other implants. It is easier to install and requires less extensive conjunctival dissection than other large implants. Additional studies are needed to evaluate the effectiveness of the Baerveldt implant in affording long-term intraocular pressure control.

Adult↗
PubMed1993

Echographic evaluation of glaucoma shunts.

BACKGROUND: It is frequently impossible to determine by clinical examination alone if a filtering bleb is present over the equatorial plate(s) of a glaucoma shunt. This uncertainty can result in management dilemmas when patients with these devices have elevated intraocular pressures (IOPs). The authors describe how standardized echography can be used to determine if fluid is present around the plates and to characterize the blebs. METHODS: Four hundred twenty-seven plates in 269 patients who had undergone single- or double-plate Molteno implantation underwent standardized echography (both A- and B-scan examinations) to determine if blebs were present around the plates, primarily when results of slit-lamp examinations had been inconclusive. Bleb sizes, locations, and characteristics also were evaluated. RESULTS: Sixty-five percent of the plates had associated blebs, which were graded according to their sizes (small, medium, and large, in 29%, 44%, and 27% of plates with blebs, respectively). Fluid (which appeared as an echolucent area) could be seen underlying and/or overlying the plates (which appeared as echodense lines). Larger blebs were often associated with scleral flattening. Although bleb sizes did not necessarily correlate with the levels of IOP control, the presence of a bleb on ultrasound was indicative of tube patency. CONCLUSION: Standardized echography was invaluable in the postoperative management of patients who had undergone Molteno implantation because it demonstrated the presence or absence of blebs and characterized them when results of slit-lamp examinations had been inconclusive. This technique also can be used to evaluate similarly designed aqueous shunting devices.

Adult↗
PubMed1993

The synergistic effects of cyclosporine and endothelin--demonstration of an important cardiodepressor action.

Cyclosporine represents the foundation for current immunosuppressive therapy following solid organ transplantation. CsA use is associated with renal insufficiency and systemic hypertension. We hypothesized that CsA would enhance the vascular actions of endothelin (ET). Three groups of anesthesized dogs (n = 15) were studied. Group 1 received CsA alone (1 mg/kg), group 2 received ET alone (1 ng/kg/min), and group 3 received combined CsA (1 mg/kg) and ET (1 ng/kg/min). The hemodynamic and renal effects were evaluated after 30 min. Combined treatment resulted in a profound reduction in mean arterial pressure (-62 +/- 14 mmHg (P < .05) and cardiac output (-2.2 +/- 0.4.1/min (P < .05). The reduction in mean arterial pressure and cardiac output were significantly greater than that observed with CsA or ET alone. Systemic vascular resistance was not significantly changed. Combined CsA and ET resulted in a significant reduction in renal blood flow (195 +/- 18 to 101 +/- 11 ml/mm P < .05) but without evidence of active renal vasoconstriction. The decline in GFR (31.8 +/- 5.6 ml/min to being unmeasurable) was of greater magnitude than the change in renal blood flow, suggesting enhanced afferent anteriolar vasoconstriction or an alteration in the ultrafiltration coefficient. These studies demonstrate an important and synergistic cardiodepressor effect when CsA and ET are combined.

Animals↗
PubMed1992

Incidence and management of glaucoma after intravitreal silicone oil injection for complicated retinal detachments.

BACKGROUND: Intravitreal silicone oil injection used for managing complicated retinal detachments can be associated with elevated intraocular pressure (IOP). This study was undertaken to determine the incidence of glaucoma in patients who underwent silicone oil injection, as well as to evaluate the effectiveness of medical and surgical therapy in patients in whom glaucoma developed. METHODS: The postoperative courses of 50 eyes of 47 consecutive patients who underwent pars plana vitrectomy and silicone oil injection for the management of complicated retinal detachments were reviewed retrospectively. The outcomes of patients who underwent silicone oil removal and/or glaucoma surgery also were evaluated. RESULTS: The mean overall postoperative IOP before any glaucoma surgery was 16.7 +/- 9.3 mmHg (range, 0 to 45 mmHg), with a mean follow-up of 16.6 +/- 12.1 months (range, 2 to 51 months). Twenty-four (48%) eyes had postoperative IOPs of at least 25 mmHg and IOP elevations of at least 10 mmHg above the preoperative levels. Twenty-one (42%) eyes underwent complete removal of silicone oil and/or glaucoma surgery to effect IOP control. The IOPs were controlled to 21 mmHg or less (but > 5 mmHg) in 8 of 14 eyes that underwent removal of silicone oil alone, in 3 of 5 eyes that underwent Molteno implantation, and in 1 eye that underwent Nd:YAG transscleral cyclophotocoagulation, but not in 1 eye that underwent a modified Schocket procedure (mean follow-up, 13.5 +/- 11.0 months; range, 0.2 to 33 months). CONCLUSION: Intraocular pressure elevation is a common occurrence after intravitreal silicone oil injection. The underlying mechanism may often be multifactorial in nature. Patients in whom uncontrolled IOP develops may benefit from aggressive medical and/or surgical treatment with silicone oil removal, glaucoma implants, or cyclodestructive procedures.

Adolescent↗
PubMed1992

Which is better? One or two? A randomized clinical trial of single-plate versus double-plate Molteno implantation for glaucomas in aphakia and pseudophakia.

PURPOSE: Previous studies have suggested that primary double-plate Molteno implantation may be beneficial. Therefore, the authors performed a randomized clinical trial to evaluate the relative effectiveness and safety of single- versus double-plate Molteno implantation. METHODS: From March 1988 to February 1990, 132 patients who underwent Molteno implantation for medically uncontrollable non-neovascular glaucomas in aphakia or pseudophakia were randomly assigned to receive either single- or double-plate implants. RESULTS: The 1- and 2-year life-table success rates (success [survival] defined as 6 mmHg < or = final intraocular pressure [IOP] < or = 21 mmHg without additional glaucoma surgery or devastating complication) were 55% and 46% with single-plate implantation and 86% and 71% with double-plate implantation, respectively. The final postoperative visual acuities were within one line of the preoperative visual acuities or had improved in 73% and 80% of patients, respectively. Choroidal hemorrhages and/or effusions, corneal decompensation, flat anterior chambers, and phthisis bulbi were more common in the patients who had undergone double-plate Molteno implantation; however, transient elevations of IOP during the first few postoperative months were more common in the patients who had undergone single-plate Molteno implantation. CONCLUSIONS: Double-plate Molteno implantation more frequently affords IOP control than single-plate Molteno implantation; however, double plates are associated with greater risks of choroidal hemorrhages and/or effusions, corneal decompensation, flat anterior chambers, and phthisis bulbi.

Adolescent↗
PubMed1992

Clinical experience with the single-plate Molteno implant in complicated glaucomas. Update of a pilot study.

Ninety-six patients who had undergone single-plate Molteno implantation for glaucomas with poor surgical prognoses were re-evaluated for long-term results. Control of intraocular pressure was achieved with one single-plate implant to a level less than 22 mmHg (but greater than 5 mmHg) without reoperation or devastating complications in 46% of the aphakic/pseudophakic eyes, 25% of eyes after failed filters, 25% of eyes with neovascular glaucomas, and 26% of eyes in patients younger than 13 years of age (life-table analysis at 5 years). Five-year success rates improved to 53%, 71%, 40%, and 56%, respectively, when data from second plates were included. Visual acuities improved or remained the same after one or two plates were implanted in 47% of aphakic/pseudophakic eyes, 17% of eyes after failed filters, 65% of eyes with neovascular glaucomas, and 63% of eyes in patients younger than 13 years of age on whom Snellen acuity was available. The most frequent overall complications after implantation of one or two plates included: corneal edema (19%), corneal graft decompensation (13%), and cornea-tube touch, retinal detachment, and cataract (8% each).

Adolescent↗
PubMed1992

The sodium retaining effects of cyclosporine.

The effect of chronic cyclosporine administration on volume regulation was studied in mongrel dogs. Dogs received either cyclosporine (20 mg/kg/day p.o.; N = 7) or vehicle (N = 6) while being maintained on a constant sodium diet. Dogs had measurement of baseline vasoactive hormones. Daily sodium excretion was determined. Following eight days of drug administration, dogs were anesthetized, pre-volume expansion data was collected, and dogs underwent a one hour, 10% body weight 0.9% saline volume expansion. Daily sodium balance was +8.6 +/- 2.2 mEq in the cyclosporine group versus 0.4 +/- 1.8 mEq (P less than 0.05) in the control group after 8 days. Prior to acute volume expansion, aldosterone was 22.5 +/- 7.1 ng% in the cyclosporine group versus 4.7 +/- 0.7 ng% in controls (P less than 0.05). ANF was suppressed in the animals receiving cyclosporine. In response to volume expansion, the cyclosporine group demonstrated an attenuation of maximum urine flow by 56%, fractional excretion of sodium by 52%, and electrolyte free water clearance by 75% when compared to controls (P less than 0.05). We demonstrate that chronic cyclosporine administration activates the renin-angiotensin-aldosterone system, suppresses circulating ANF, and results in chronic sodium retention. Additionally, cyclosporine attenuates the natriuretic and diuretic response to acute volume expansion.

Animals↗
PubMed1992

Role of renal Na+,K(+)-ATPase in the regulation of sodium excretion under normal conditions and in acute congestive heart failure.

BACKGROUND: Cardiac glycosides have traditionally been used as inotropic agents in the treatment of congestive heart failure (CHF). The renal actions of cardiac glycosides independent of inotropic effects are not characterized. The presence of endogenous digitalis-like factors (EDLFs) with characteristic Na+,K(+)-ATPase activity has been postulated in volume-expanded states such as CHF, and recent studies have demonstrated that at least one EDLF shares structural homology with ouabain. This study was undertaken to evaluate the renal actions of ouabain in normal dogs and those with CHF. METHODS AND RESULTS: After surgical preparation, normal dogs (n = 6) and dogs in pacing-induced CHF (n = 6) received intrarenal ouabain in sequential doses of 0.167 micrograms/kg/min, 0.334 micrograms/kg/min, and 0.668 micrograms/kg/min. Hemodynamics and renal function were evaluated during the infusion. There was no change in heart rate or mean arterial pressure during the infusion compared with baseline in both groups. Sodium excretion and urine volume significantly increased in both groups. Plasma renin activity, activated by the onset of pacing in the CHF group, was inhibited by the administration of intrarenal ouabain in this group only. CONCLUSIONS: These studies demonstrate that ouabain has diuretic and natriuretic actions independent of cardiac hemodynamics that are preserved in CHF. Furthermore, intrarenal ouabain suppresses activation of renin in CHF.

Acute Disease↗
PubMed1991

Combined Molteno implantation and pars plana vitrectomy for neovascular glaucomas.

Ten patients underwent combined Molteno implantation and pars plana vitrectomy as the primary nonlaser surgical treatment of neovascular glaucoma associated with diabetic retinopathy (9 patients) or central retinal vein occlusion (1 patient). Combined surgery was performed most frequently because media opacities precluded adequate preoperative retinal ablation. Follow-up ranged from 3 to 43 (mean +/- standard deviation, 18.0 +/- 13.2) months. Six patients achieved final intraocular pressures less than 22 mmHg. Visual acuities remained the same or improved in four patients. Four patients had uncomplicated courses. Among the other patients, complications included: recurrent vitreous hemorrhage and retinal detachment (3 patients each); hyphema (2 patients); and tube block, extensive fibrin formation, epiretinal membrane, and total retinal necrosis (1 patient each).

Adult↗
PubMed1989

BKm minisatellite sequences are not sex associated but reveal DNA fingerprint polymorphisms in rainbow trout.

GATA-GACA repetitive sequences first isolated from a female snake (termed BKm sequences) and associated with sex chromosomes in some species were hybridized to DNA from rainbow trout (Salmo gairdneri). Genomic DNA was studied from three groups of rainbow trout: (i) randomly selected males and females from an outbred group, (ii) androgenetic individuals from an inbred strain, and (iii) parents and offspring of an outbred strain. Three restriction enzymes (EcoRI, HaeIII, or HinfI) were used to digest the genomic DNA. The DNA was electrophoresed in agarose gels, transferred to nylon membranes, and the GATA-GACA repetitive sequence probe was hybridized to this DNA. There was no evidence of sex-associated patterns of hybridization with the enzymes used. However, the sequences reveal DNA fingerprint polymorphisms which appear to be inherited in a stable manner.

Animals↗
PubMed1986

Mosaic variegated trisomy (42,XY/43,XY, + variable) in a male pigtail macaque monkey.

We identified an infant male pigtail macaque monkey with a bizarre karyotype which, to the best of our knowledge, has never before been reported in any species. Examination of 107 nuclei from cultured lymphocytes revealed 81 (75.7%) to be trisomic, but with the supernumerary chromosome varying from cell to cell, trisomy 16 being the most common. A small percentage (11.2%) of the nuclei had a normal 42,XY karyotype, and the balance, with the exception of one apparent monosomic (possibly a technical artifact), had multiple chromosome abnormalities. Examination of cultured skin fibroblasts revealed a similar karyotype. We called this karyotype a mosaic variegated trisomy. At birth, the animal had a cleft lip and palate and situs inversus of the heart. He subsequently showed significant developmental delay and apparent mental retardation. There were no clinical symptoms of hematological malignancy, which often have associated acquired chromosome abnormalities such as those described here. The animal survived for 2 yr and 8 mo under intensive care.

Animals↗
PubMed1980

Ring chromosome 2 in a child with growth failure and few congenital abnormalities.

A ring chromosome 2 mosaic [46,XX/46,XX,r(2)(p25q37)] was found in a newborn female with severe intrauterine growth retardation (IUGR), postnatal growth failure, and a few minor abnormalities. Psychomotor development has been normal to 19 months old. A ring chromosome 2 is present in 77.8% of the nuclei examined and is not found in the parents or a sibling. G- and R-banding reveal the break points to be p25q37. The presence of a normal cell line indicates that the chromosome abnormality arose after conception.

Abnormalities, Multiple↗
PubMed1978

Effects of morphine and chlorpromazine on the detection of shock.

A discrete-trial, two-choice, 'yes-no' procedure was used to determine the extent to which the perceptual effects of compounds such as morphine and chlorpromazine (CPZ) can be attributed to drug-induced changes in ability to detect shock stimuli (sensitivity). Both morphine (4.0, 5.0, and 6.0 mg/kg) and CPZ (0.25, 0.50, and 1.0 mg/kg) significantly reduced accuracy and increased the times (i.e., lowered the speeds) to initiate trials and to make choice responses. The effects of morphine appeared to be somewhat greater than those of CPZ, particularly at the lowest shock intensity (0.05 mA). When compared to appropriate saline control days, morphine, but not CPZ, significantly reduced accuracy of discrimination on trials when shocks were presented, whereas CPZ, but not morphine, reduced accuracy on no-shock trials. The effects of morphine, but not of CPZ, on accuracy (both overall and on shock trials) decreased as shock intensity increased. The effects of shock intensity were generally inversely related to the effects of morphine and directly related to the effects of CPZ.

Animals↗