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Biomedical subjects

R H Gross

Publications and source records attributed to R H Gross.

At least 19 recordsLinked to original sources
PubMed2001

Management of increased vitreous pressure during penetrating keratoplasty using pars plana anterior vitreous aspiration.

PURPOSE: To describe the technique, outcomes, and complication rates for a method of pars plana vitreous aspiration to control excessive vitreous pressure during penetrating keratoplasty. METHODS: All cases of penetrating keratoplasty were reviewed retrospectively in a large cornea subspecialty private practice over a 5-year period, and 70 cases of penetrating keratoplasty complicated by excessive posterior pressure were identified. Study eyes were treated with a pars plana vitreous aspiration technique to relieve excessive posterior vitreous pressure. The main study parameters included preoperative best corrected visual acuity (BCVA), postoperative BCVA at the last recorded follow-up visit, refractive cylinder at 1 year, complications related to surgery, and other conditions that may have influenced visual function. The mean follow-up period was 24.5 months with a range of 1 to 61.1 months. RESULTS: Adverse outcomes during the extended period of follow-up included rejection in 11 of 70 eyes, graft failure in 7 of 70 eyes, glaucoma in 4 of 70 eyes, and postoperative cystoid macular edema (CME) in 5 of 70 eyes. Posterior capsulotomies using the neodymium-yttrium aluminum garnet laser were necessary in 10 of 70 patients during the follow-up period. The average magnitude of refractive astigmatism at 1 year after surgery was 3.73 diopters (D) with a range of 0 to 8 D. There were no known retinal complications other than CME and no complications that could be directly attributed to the pars plana vitreous aspiration technique. CONCLUSIONS: Pars plana anterior vitreous aspiration is a safe and effective technique for controlling increased vitreous pressure, which can complicate penetrating keratoplasty.

Adolescent↗
PubMed1998

Foot and ankle injuries and disorders.

This chapter analyses the mechanics of walking and running gait and delineates the terminology used to describe foot and ankle injuries. A helpful anatomic review precedes explanations of the mechanisms of sports injuries in this area. The author documents the correct diagnoses and treatments for foot and ankle sprains, fractures, and stress injuries.

Adolescent↗
PubMed1997

Corneal perforation associated with argon laser photocoagulation for a retinal tear.

PURPOSE: To report a corneal perforation during argon laser photocoagulation around a retinal tear following pneumatic retinopexy. METHODS: The patient was examined and found to have a corneal perforation with pigment in the base of the wound. To help explain this phenomenon, we evaluated the ability of argon blue-green laser to create a corneal perforation in a cadaver eye. RESULTS: In a cadaver eye, we induced a corneal perforation with argon laser only when a pigmented substance was present on the corneal surface. CONCLUSIONS: We hypothesize that pigmented material such as an eyelash or mascara caught between the cornea and contact lens interface may have facilitated this rare complication. Clinicians should be wary of any pigmented substance on the surface of the cornea or ophthalmoscopic lens when performing argon laser photocoagulation.

Aged↗
PubMed1997

Comparison of astigmatism after penetrating keratoplasty by experienced cornea surgeons and cornea fellows.

PURPOSE: We compared surgically induced astigmatism after penetrating keratoplasty performed by supervised cornea fellows and experienced cornea surgeons. METHODS: Data were collected by retrospective chart review of 166 cases (166 eyes) of penetrating keratoplasty: 63 performed by two cornea surgeons and 103 by four cornea fellows. Astigmatism was calculated using scalar and vector methods. Vector analysis was performed on 109 of 166 eyes. Two techniques were compared: intraoperative keratometry and suture adjustment and the torque-antitorque running suture technique with no intraoperative keratometry or suture adjustment. RESULTS: Mean surgically induced scalar astigmatism changed from preoperative astigmatism by 3.27 diopters (fellows) and 2.94 diopters (attending surgeons). In 109 cases, surgically induced vector cylinder changed from peroperative astigmatism by 4.21 diopters at 98 degrees (fellows) and 4.25 diopters at 114 degrees (surgeons). Surgically induced vector astigmatism changed from preoperative astigmatism by 4.67 diopters at 93 degrees in the first 6 months (fellows) and by 3.79 diopters at 103 degrees in the second 6 months. Analysis of x-axis and y-axis components of the surgically induced vector cylinder showed that the majority of the astigmatism was induced in the y-axis and that this difference was significant (P < .001) in all comparisons, independent of technique or surgeon group. CONCLUSIONS: Penetrating keratoplasty performed by supervised cornea fellows resulted in similar rates of surgically induced vector astigmatism, surface asymmetry, and surface regularity as that by experienced surgeons. Fellows induced significantly more with-the-rule astigmatism, but this tendency decreased with further training. Penetrating keratoplasty astigmatic outcomes were not significantly different whether or not intraopertive keratometry and suture adjustment were utilized. This study supports the concept that increased experience with corneal transplantation improves the outcome of penetrating keratoplasty by using the criterion of postoperative astigmatism as a measures.

Astigmatism↗
PubMed1997

Floppy eyelid syndrome in a child with chronic unilateral conjunctivitis.

PURPOSE: To report a 2-year-old child who had chronic unilateral conjunctivitis and spontaneous left upper eyelid eversion during sleep consistent with the floppy eyelid syndrome. METHODS: The patient's parents used a video camera to document nocturnal ectropion of the left upper eyelid. Examination demonstrated left upper eyelid swelling and left palpebral conjunctival hyperemia with papillary hypertrophy. RESULTS: All signs and symptoms of the floppy eyelid syndrome resolved with taping of the left upper and lower eyelids to close the palpebral fissure and to prevent ectropion during sleep, and with application of ocular lubricants. CONCLUSIONS: Floppy eyelid syndrome may manifest in childhood without other contributing conditions and should be considered in the differential diagnosis of chronic papillary conjunctivitis in patients at any age.

Child, Preschool↗
PubMed1997

Proposed curriculum model for resident education in pediatric orthopaedic surgery.

A curriculum developed for pediatric orthopaedic residency training is described. The curriculum is practice based, emphasizing those components thought to be necessary for orthopaedic practice. Highly technical or esoteric topics are deemphasized, because they are not relevant to practice capabilities at the end of residency training. The curriculum is designed to serve as a guide for educational direction in pediatric orthopaedic residency training, and not as a description of competency. Resource materials are being developed to provide the educator with relevant clinical material, objectives, and bibliography. The advantages of a practice based curriculum warrant further development of this model for other orthopaedic subspecialties.

Clinical Competence↗
PubMed1996

Corneal astigmatism after phacoemulsification and lens implantation through unsutured scleral and corneal tunnel incisions.

PURPOSE: We compared the changes in corneal astigmatism after phacoemulsification and intraocular lens implantation in 93 consecutive eyes with unsutured 4-mm superior scleral tunnel incisions to those through 105 consecutive eyes with unsutured 3.2- to 3.5-mm temporal corneal tunnel incisions. METHODS: Keratometry measurements were obtained preoperatively and at postoperative day 1, week 1, and week 6. Group differences in scalar and vector astigmatism were compared by using analysis of variance methods. RESULTS: Mean scalar astigmatism in the scleral incision group changed from preoperative astigmatism by 0.65 diopter at postoperative day 1, 0.37 diopter at postoperative week 1, and 0.13 diopter at postoperative week 6. Mean scalar astigmatism in the corneal incision group changed from preoperative astigmatism by 0.39 diopter at postoperative astigmatism by 0.39 diopter at postoperative day 1, 0.21 diopter at postoperative week 1, and 0.13 diopter at postoperative week 6. Mean vector astigmatism in the scleral incision group changed 1.26 diopters at 80 degrees at postoperative day 1, 1.05 diopters at 83 degrees at postoperative week 1, and 0.42 diopter at 103 degrees at postoperative week 6. Mean vector astigmatism in the corneal incision group changed 0.77 diopter at 90 degrees at postoperative week 1, and 0.61 diopter at 89 degrees at postoperative week 6. The differences were statistically significant (P = .003) only by vector analysis at the postoperative day 1 examination. CONCLUSIONS: We found significantly greater with-the-rule change in astigmatism in the scleral incision group than in the corneal incision group on the first postoperative day. The effect disappeared by the sixth postoperative week.

Astigmatism↗
PubMed1995

Corneal pharmacokinetics of topical clarithromycin.

PURPOSE: To evaluate the pharmacokinetics of topically applied clarithromycin, a new macrolide antibiotic, at various concentrations in a rabbit model. METHODS: Clarithromycin in dosages of 10, 20, and 40 mg/ml was administered topically every 2 hours for 48 hours to three groups of 16 New Zealand albino rabbits. Both corneas were treated. Right corneas were deepithelialized with n-heptanol. At 6, 12, 24, and 48 hours, tissue concentrations were determined in four animals from each group. RESULTS: Tissue drug concentrations increased with drug dosage and duration of therapy. Drug concentrations were significantly higher at 48 hours than at 6 hours, 12 hours, and 24 hours for both epithelialized and deepithelialized eyes in the 20 mg/ml and 40 mg/ml treatment groups (all P < or = 0.0015). A steady state concentration was not achieved in any group. Tissue drug concentrations were higher in deepithelialized corneas for each dose after 6 hours, although differences were not significant (all P > 0.059). Highest mean drug concentration at 48 hours was 241 micrograms/g in animals receiving 40 mg/ml of clarithromycin. After 6 hours, tissue concentrations in some groups were above MIC90 for many Chlamydia sp., Streptococcus sp., and Staphylococcus sp., and by 12 hours, concentrations were greater than MIC90 in all groups for many nontuberculous mycobacteria. CONCLUSIONS: Topical clarithromycin achieves therapeutic levels in corneal tissue in a rabbit model. Clarithromycin might be a useful broad-spectrum antibiotic for topical use in humans.

Absorption↗
PubMed1994

Chemical induction of stress proteins does not induce splicing thermotolerance under conditions producing survival thermotolerance.

Cell survival during a severe heat stress can be enhanced when heat shock proteins are induced prior to the severe heat treatment. Induction can be accomplished either by heat or chemical treatments. The increase in survival at these severe elevated temperatures after pretreatment has been referred to as thermotolerance, which we now refer to as survival thermotolerance. It has also been shown previously that mild heat treatment allows splicing in cells subjected to a severe heat treatment, now referred to as splicing thermotolerance. The experiments shown here demonstrate that even though chemical induction of the heat shock proteins leads to survival thermotolerance, this same treatment does not induce splicing thermotolerance. These are the first results that demonstrate at least two distinct aspects of thermotolerance.

Animals↗
PubMed1993

Musculoaponeurotic fibromatosis (extraabdominal desmoid tumor) in a child with idiopathic multicentric osteolysis.

The fibromatoses are a group of benign proliferations of fibrous tissue with clinical behavior ranging from that of truly malignant tumors to that of benign reactive fibrous proliferations. Some of the superficial fibromatoses are fairly common, but the deep ones, also known as desmoid tumors or musculoaponeurotic fibromatoses, are rare. Idiopathic multicentric osteolysis is a rare skeletal disorder of childhood that causes progressive destruction of bones and renal failure. We recently saw a young girl with both extraabdominal musculoaponeurotic fibromatosis and idiopathic multicentric osteolysis. The classification, diagnosis, and treatment of the deep fibromatoses are reviewed, and the possible association between the minor bone changes occasionally reported in musculoaponeurotic fibromatosis and idiopathic multicentric osteolysis is discussed.

Biopsy↗
PubMed1992

Splicing thermotolerance maintains Pre-mRNA transcripts in the splicing pathway during severe heat shock.

Thermotolerance, the ability of cells and organisms to withstand severe elevated temperatures after brief exposure to mild elevated temperatures, has been studied in numerous laboratories. Survival thermotolerance is defined as the increase in cell or organism survival at severe elevated temperatures after a pretreatment at mild elevated temperatures. This study examines splicing thermotolerance in Drosophila melanogaster, the ability to splice pre-mRNAs made at the severe temperature (38 degrees C) after a brief pretreatment at a milder temperature (35 degrees C). It is probably one of a number of mechanisms by which cells adapt to heat shock. These experiments demonstrate that pre-mRNAs synthesized at the severe temperatures in splicing thermotolerant cells, although protected in splicing-competent complexes, are not actually processed to mature mRNAs until the cells are returned to their normal temperature. We have also studied the kinetics of acquisition and loss of splicing thermotolerance. As little as 10 min of pretreatment at 35 degrees C was sufficient to provide full splicing thermotolerance to a 30-min severe heat shock of 38 degrees C. Pretreatments of less than 10 min provide partial splicing thermotolerance for a 30-min severe heat shock. Full splicing thermotolerance activity begins to decay about 4 h after the cessation of the 35 degrees C incubation and is completely lost by 8 h after the pretreatment. The kinetics experiments of pre-mRNAs synthesized during the 38 degrees C treatment in splicing thermotolerant cells indicate that one or more splicing thermotolerance factors are synthesized during the 35 degrees C pretreatment which interact with pre-mRNA-containing complexes to keep them in a splicing-competent state. These kinetic experiments also indicate that in cells which are partially splicing thermotolerant, the pre-mRNAs synthesized early during the 38 degrees C incubation are protected, whereas those synthesized late are not. In the absence of splicing thermotolerant factors, the pre-mRNA-containing complexes leave the normal splicing pathway and are allowed to exit to the cytoplasm.

Animals↗
PubMed1990

Distal femoral physeal problem fractures.

Treatment options in the past for distal femoral physeal fractures have varied from closed reduction to open reduction with internal fixation to balanced skeletal traction. In this study, ten patients with distal femoral physeal fractures treated with closed reduction and casting or skeletal traction are reviewed. Seven fractures lost position in comparison with original reduction films. Nine patients developed subsequent deformity. No consensus exists regarding the use of open versus closed treatment with internal fixation. This review of closed treatment yielded a high rate of unacceptable results. Initial anatomic reduction with rigid fixation of physeal injuries about the ankle has been demonstrated to decrease the incidence of growth deformity. The authors' experience and a review of the literature suggest that a similar approach is applicable to distal femoral physeal fractures.

Adolescent↗
PubMed1990

The Gene Construction Kit: a new computer program for manipulating and presenting DNA constructs.

The Gene Construction Kit is a new tool for manipulating and displaying DNA sequence information. Constructs can be displayed either graphically or as formatted sequence. Segments of DNA can be cut out with restriction enzymes and pasted into other sites. The program keeps track of staggered ends and notifies the user of incompatibilities and offers a choice of ligation options. Each segment of a construct can have its own defined thickness, pattern, direction and color. The sequence listing can be displayed in any font and style in user defined grouping. Nucleotide positions can be displayed as can restriction sites and protein sequences. The DNA can be displayed as either single- or double-stranded. Restriction sites can be readily marked. Alternative views of the DNA can be maintained and the history of the construct automatically stored. Gel electrophoresis patterns can be generated and can be used in cloning project design. Extensive comments can be stored with the construct and can be searched rapidly for key words. High quality illustrations showing multiple editable constructs with added graphics and text information can be generated for slides, posters or publication.

Amino Acid Sequence↗
PubMed1988

Disorders of the sacro-iliac joint in children.

The cases of seventeen children whose ages ranged from two to eighteen years and who were treated for a disorder of a sacro-iliac joint between 1975 and 1983 were reviewed retrospectively. Thirteen children were acutely ill, with a temperature of more than 38 degrees Celsius, and four had chronic symptoms that had persisted for three weeks to one year. Pain in the hip, thigh, and buttock was the most common symptom. Of the thirteen acutely ill patients, eleven had septic arthritis of a sacro-iliac joint, while one who had ankylosing spondylitis and one who had juvenile rheumatoid arthritis had acutely painful arthritis of a sacro-iliac joint. Of the four patients who had chronic symptoms, two had septic arthritis of a sacro-iliac joint; one, ankylosing spondylitis with sacro-iliac involvement; and one, eosinophilic granuloma of the ilium. Thus, thirteen patients had septic arthritis of a sacro-iliac joint and four had some other disorder. For the seventeen children who had acute or chronic symptoms, at admission the white blood-cell count ranged from 3,500 to 26,200 per cubic millimeter (average, 11,100 per cubic millimeter) and the sedimentation rate, as determined by the Westergren technique, ranged from twenty-two to sixty-five millimeters per hour (average, fifty millimeters per hour). Twelve of the plain radiographs of the seventeen patients were negative. The initial bone scans of all seventeen patients were positive in eleven and negative in six. Of these six, five had septic arthritis and one, juvenile rheumatoid arthritis. A computed tomographic scan was performed in four patients and was positive in all of them: three had septic arthritis and one had ankylosing spondylitis. Organisms were cultured successfully from blood, from material aspirated from the sacro-iliac joint, or from stool of all thirteen patients who had sepsis. The thirteen infections responded well to appropriate antibiotics, which were administered intravenously to seven patients and first intravenously and then orally to six.

Adolescent↗