Search PubMed⌕ Search

Biomedical subjects

J D Green

Publications and source records attributed to J D Green.

At least 19 recordsLinked to original sources
PubMed1998

Bone cement reconstruction of the ossicular chain: a preliminary report.

OBJECTIVE: To determine the feasibility and efficacy of using a bone cement, Oto-Cem, to reconstruct the ossicular chain. STUDY DESIGN: Prospective clinical trial on nine consecutively chosen adult patients with ossicular chain defects. PATIENTS AND SETTING: Nine patients with ossicular chain defects involving the long process of the incus were treated at the Carolina Ear and Hearing Clinic. The ossicular chain was reconstructed using bone cement by itself or in conjunction with a stapes prosthesis. MAIN OUTCOME MEASURES: Preoperative audiograms were compared with audiograms 3, 6, and 12 months after reconstruction. RESULTS: There was a mean pure-tone average (PTA) improvement of 15 dB in patients undergoing incus to stapes suprastructure reconstruction with the bone cement. The incus to mobile footplate reconstruction (using a stapes prosthesis attached to the newly reconstructed incus) resulted in a 34-dB PTA postoperative improvement. Two of the three patients with incus to oval window repairs experienced a 10-dB improvement in PTA. One of the three patients experienced a loss in speech discrimination and a 2-dB loss in PTA. CONCLUSIONS: Despite the limited number of patients, this preliminary study demonstrates the effectiveness of Oto-Cem in reconstructing a foreshortened incus. There was a substantial hearing improvement in all but one patient in the incus to stapes or the incus to footplate categories.

Auditory Threshold↗
PubMed1997

The effects of methoxychlor on early sea urchin development.

Methoxychlor (MXC) is a widely used pesticide which has been found in water sources near agricultural sites. Embryos of aquatic organisms are likely to encounter MXC due to land runoff. The sea urchin embryo (Strongylocentrotus purpuratus) was used as a model system to document the effects of MXC on early development up to the pluteus stage. Fertilized eggs and embryos were exposed to several concentrations (0.1, 1.0, 10, and 100 ppm) of the pesticide in both chronic and acute exposure regimens. With chronic exposure, percentages of embryos completing normal first cleavage decreased with increased concentrations of MXC, and subsequent cleavages became even more irregular in that blastomeres divided asymmetrically and asynchronously. Ten parts per million MXC allowed development through the hatched blastula stage, whereas embryos in 100 ppm MXC did not hatch. In acute exposure trials, fertilized eggs were pulsed (i.e., exposed for brief durations) to MXC for 30, 60, or 90 min. The MXC was then washed out. Recovery of normal development was proportional to the amount and duration of MXC exposure. Development was delayed in embryos exposed to 100 ppm MXC for 30 or 60 min. The embryos exposed to 100 ppm MXC for 90 min were abnormal as early as the four-cell stage, and by 72 hr more than 90% had abnormal gut development, indicating disruption of gastrulation. These data show that MXC exposure resulted in retardation of cleavage and abnormal gastrulation, basic morphogenetic processes.

Animals↗
PubMed1996

Otocephalus: histopathology and three-dimensional reconstruction.

Otocephaly is a lethal malformation of the first and second branchial arches, which consists of ventromedial displacement of the external ear structures (synotia), mandibular aplasia (agnathia), absence of the tongue (aglossia), and microstomia. We present the first complete description of the temporal bone findings in a case of otocephalus. A three-dimensional computer-assisted reconstruction of the right temporal bone was performed, allowing a unique graphic analysis. An extremely low-lying middle fossa tegmen was noted with malrotation of the middle ear structures. Severe ossicular malformations were also found. An anomalous course of the internal carotid artery was noted with indentation of the basal turn of the cochlea. All three layers of the otic capsule were incompletely developed. Cochlear bony dehiscences were noted. These findings are consistent with early arrest of fetal development and malrotation caused by lack of growth pressure from the mandibular arch. Implications of these findings in the embryologic development of the ear are discussed.

Abnormalities, Multiple↗
PubMed1996

Design of biological equivalence programs for therapeutic biotechnology products in clinical development: a perspective.

The determination of biological equivalence requires that studies are conducted to establish that two molecules, two formulations, of two dosing regimens, for example, are indistinguishable with respect to safety and efficacy profiles that have been previously established. The criteria that are used to establish biological equivalence will depend on the nature of the change (e.g., molecular, process, formulation), the stage of the development program, the duration of treatment, and the intended clinical indications. Key components of an equivalence program include chemical characterization, in vitro and in vivo bioactivity against reference material, pharmacokinetics, and safety. Special considerations for patient populations, endogenous concentrations, environmental factors, immunogenicity, assay methodology, biochemical identity, pharmacodynamic equivalence, and statistical methodology are discussed. In addition, the role of preclinical in vivo assessments is addressed. Specific case studies provide insight into the varied nature of approaches that are currently employed.

Biotechnology↗
PubMed1996

A modification of sub-mental intubation.

In patients who have sustained base of skull fractures, the mode of intubation is controversial, with many anaesthetists arguing against nasal intubation. In several maxillofacial procedures temporary intermaxillary fixation (IMF) in the intraoperative period may be essential to achieve optimal results in fixation. For patients with combined facial and base of skull injury, tracheotomy may have to be performed. The submental approach to intubation allows IMF to be used without resort to nasal intubation or tracheotomy. We describe a modification of the original technique which is applicable to any reinforced tracheal tube and which does not compromise the airway.

Adult↗
PubMed1996

Conservative management of acoustic neuroma: an outcome study.

OBJECTIVE: This study analyzed selection criteria, clinical outcome, and tumor growth rates in patients with acoustic neuromas in whom the initial management strategy was observation. METHODS: A retrospective review of patients with conservatively managed unilateral acoustic neuromas was conducted. Minimum follow-up was 6 months. Patients with neurofibromatosis Type II were excluded. Differences in tumor growth rates were analyzed by use of the Wilcoxon rank sum test. RESULTS: Sixty-eight patients (31 men and 37 women) with a mean age of 67.1 years were followed for an average of 3.4 years after diagnosis. The reasons for a trial of observation included advanced age (55%), patient preference (21%), minimal symptoms (9%), poor general medical condition (7%), asymptomatic tumor (4%), and tumor in the only hearing ear (4%). Fifty-eight patients (85%) were successfully managed with observation alone. Ten patients (15%) ultimately required treatment (nine received microsurgical treatment and one patient underwent radiosurgical intervention) at a mean time interval of 4.0 years after diagnosis. Forty-eight tumors (71%) showed no growth and 20 (29%) enlarged during the study period. The mean tumor growth rate at the 1-year follow-up was significantly higher in the group requiring treatment (3.0 mm) than in the group not requiring treatment (0.36 mm) (P < 0.0001). Thus, the tumor growth rate at the 1-year follow-up was a strong predictor of the eventual need for treatment. CONCLUSION: Observation is a reasonable management strategy in carefully selected patients with acoustic neuromas. Diligent follow-up with serial magnetic resonance imaging is recommended, because some tumors will enlarge to the point at which active treatment is required.

Aged↗
PubMed1996

Efficacy of an intraperitoneal antibiotic to reduce the incidence of infection in the trauma patient: a prospective, randomized study.

BACKGROUND: Antibiotic therapy in patients with blunt trauma remains an area of investigation. This study was undertaken in trauma patients evaluated with diagnostic peritoneal lavage to determine the effect of an intraperitoneal antibiotic on the following factors: infectious complications, length of hospital stay, and mortality. METHODS: A prospective, randomized double-blinded study compared using either 500 mg of intraperitoneal kanamycin or a saline control in 69 adult trauma patients requiring diagnostic peritoneal lavage was conducted over a 24-month period. Advanced trauma life support indications for performing diagnostic peritoneal lavage were used. Patients were randomized to receive 50 mL of solution intraperitoneally through a lavage catheter and were evaluated for all septic complications, length of hospital stay, and outcome. RESULTS: Over a 24-month period, 40 patients received kanamycin, and 29 patients received a placebo. Of patients receiving kanamycin, 27.5 percent experienced infectious complications compared to 65.5 percent of the control patients (p = 0.001, chi-square analysis). The average length of stay in the intensive care unit was 4.18 days in the kanamycin group and 6.96 days in the control group (p = 0.04, chi-square analysis). The average length of stay was 12.32 days for patients receiving kanamycin and 17.36 days for the control group (p = 0.03, chi-square analysis). The mortality rate for each group was 13 percent. CONCLUSIONS: Intraperitoneal kanamycin given to trauma patients requiring diagnostic peritoneal lavage within the first three hours following injury reduces the incidence of infectious complications and shortens intensive care unit and hospital stay.

Abdominal Injuries↗
PubMed1995

Three-dimensional structure of a lipoyl domain from the dihydrolipoyl acetyltransferase component of the pyruvate dehydrogenase multienzyme complex of Escherichia coli.

The structure of a lipoyl domain from the pyruvate dehydrogenase multienzyme complex of Escherichia coli has been determined by means of nuclear magnetic resonance spectroscopy. A total of 549 nuclear Overhauser effect distance restraints, 52 phi torsion angle restraints and 16 slowly exchanging amide protons were employed as input for the structure calculations. These were performed using a combined distance geometry-simulated annealing strategy. The domain is a hybrid between the N and C-terminal halves of the first and third lipoyl domains, respectively, of the dihydrolipoyl acetyltransferase component of the E. coli multienzyme complex, representing residues 1 to 33 and 238 to 289 (wild-type numbering). The lipoyl-lysine residue was also replaced by glutamine. Nonetheless, its structure, two four-stranded beta-sheets forming a flattened beta-barrel, closely resembles that of the lipoyl domain from the pyruvate dehydrogenase multienzyme complex from Bacillus stearothermophilus determined previously. As before, the lipoylation site is physically exposed in a tight turn in one of the beta-sheets, and the N and C-terminal residues are close together at the other end of the molecule in adjacent strands of the other beta-sheet. Another prominently conserved feature of the structure is the 2-fold axis of quasi-symmetry relating the N and C-terminal halves of the domain. Consistent with the high level of sequence similarity between lipoyl domains of 2-oxo acid dehydrogenase multienzyme complexes from many different sources, these results confirm that all lipoyl domains are likely to have closely related structures.

Acetyltransferases↗
PubMed1995

Ossiculoplasty with polymaleinate ionomeric prosthesis.

With the continued concern over the possible transmission of viral infections through homologous middle ear implants, there is increasing pressure to develop a truly biocompatible alloplastic middle ear prosthesis. The polymaleinate ionomer, which has been used in dentistry as a filling and luting material for more than 15 years, has recently been used to construct total and partial ossicular replacement prostheses. In an attempt to evaluate these new implants, a multicenter prospective clinical trial was initiated. To date, 92 patients have undergone implantation. The follow-up interval ranged from 3 months to 22 months. Although it is premature to discuss the long-term results, the preliminary surgical experience and audiometric data with these implants are reviewed. From a surgical perspective, the ionomeric prostheses were easily contoured with a diamond burr and were not prone to shattering. Preliminary follow-up audiometric data were available on 80 patients (59 partial ossicular replacement prostheses and 21 total ossicular replacement prostheses). Of the 59 partial ossicular replacement prostheses the air-bone gaps (average of 500 Hz, 1 kHz, 2 kHz and 3 kHz) were as follows: 0 dB to 10 dB, 15 (25%) of 59; 11 dB to 20 dB, 20 (34%) of 59; 21 dB to 30 dB, 11 (19%) of 59; and greater than 30 dB, 13 (22%) of 59. Of the 21 total ossicular replacement prostheses the air-bone gaps were as follows: 0 dB to 10 dB, 6 (29%) of 21; 11 dB to 20 dB, 6 (29%) of 21; 21 dB to 30 dB, 5 (24%) of 21; and greater than 30 dB, 4 (19%) of 21.

Acoustic Stimulation↗
PubMed1995

Spiral ganglion cell survival in labyrinthitis ossificans: computerized image analysis.

Obstruction of the cochlear scale by ossification and fibrosis, which can now be imaged by computed tomography, has been proposed as a predictor of ganglion cell survival. Subjects for this histopathologic temporal bone study were 12 profoundly deaf patients with labyrinthitis ossificans. Controls without ossification were 16 normal-hearing patients and 16 profoundly deaf patients. All temporal bones were graphically reconstructed. Computerized image analysis obtained the percentage of scalar obstruction in 12 temporal bones with labyrinthitis ossificans. Statistical analyses could demonstrate no relationship between spiral ganglion cell survival and obstruction. There was much interindividual variability in ganglion cell count among the 44 temporal bones. Ganglion cell survival was significantly less in the two deafness groups than in the normal group, but did not differ significantly between the two deafness groups. Therefore, cochlear labryinthitis ossificans is not a preditor of ganglion cell survival and should not be a contraindication to cochlear implantation.

Adolescent↗
PubMed1995

Meta-analysis of antibiotics in tube thoracostomy.

The use of antibiotics for patients undergoing tube thoracostomy was determined to be highly variable based on a study conducted at a national meeting of surgeons. A meta-analysis of six randomized studies previously reported was performed. The analysis was carried out using the Confidence Profile Method software FAST*PRO. The meta-analysis was structured using dichotomous outcomes of infectious chest processes (empyema, effusion, pneumonia, wound infection, tracheitis, etc.) versus no infectious chest process in patients with and without antibiotics. The effect measures calculated included actual difference in probabilities, relative risk, percent differences in probabilities, and odds ratio. The results of this meta-analysis suggest that antibiotics should be used in patients undergoing tube thoracostomy. Antibiotic selection should maximize therapy for Staph. aureus. The implementation of this practice guideline will require the co-operation of multiple specialty oriented physicians and surgeons.

Anti-Bacterial Agents↗