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Biomedical subjects

R E Foster

Publications and source records attributed to R E Foster.

At least 37 records · Page 2Linked to original sources
PubMed1996

Useful visual outcomes after treatment of Bacillus cereus endophthalmitis.

PURPOSE: Bacillus cereus endophthalmitis occurring after penetrating ocular trauma has been almost always associated with a poor visual outcome. The purpose of our study was to review and report patients who had useful visual acuity outcomes. METHODS: The study group consisted of five patients from a single medical center with penetrating ocular trauma and endophthalmitis caused by B. cereus. The study population was derived from a review of the microbiology records, clinical records, and operative reports of patients with culture-proven, post-traumatic endophthalmitis over a 15-year period. Patients were only included if the final visual acuity outcomes were 20/200 or better. RESULTS: All five patients had penetrating ocular injuries, and four patients had a retained intraocular foreign body. Endophthalmitis was diagnosed preoperatively in three patients and intraoperatively in two patients. All patients underwent pars plana vitrectomy and injection of intravitreal and periocular antibiotics. Postoperatively, a rhegmatogenous retinal detachment developed in three patients between 4 weeks and 12 months after the injury (average, 19 weeks); all retinal detachments were reattached with additional vitreoretinal surgery. Final postoperative visual acuities were 20/200 (two patients), 20/30 (one patient), and 20/25 (two patients). The postoperative follow-up time interval ranged from 12 months to 30 months (average, 19.2 months). CONCLUSION: The current series adds further support to the observation that certain eyes with post-traumatic B. cereus endophthalmitis may be associated with preservation of anatomic integrity and restoration of useful visual acuity.

Adolescent↗
PubMed1996

Bacterial contamination of anaerobic vitreous cultures: using techniques employed for endophthalmitis.

PURPOSE: To investigate the occurrence of contaminated cultures of vitreous specimens from non-infected eyes obtained using anaerobic techniques employed for endophthalmitis. METHODS: Vitreous specimens were obtained using meticulous sterile techniques employed for endophthalmitis from seventeen patients undergoing pars plana vitrectomy for non-infective indications: vitreous hemorrhage (12 eyes), retinal detachment (3), Coat's disease (1), and congenital dislocated lens(1). Vitreous specimens were inoculated in the operating room onto an anaerobic blood agar plate and into thioglycolate broth. Bacterial growth occurring before 10 days was considered positive. RESULTS: Three organisms were isolated from three separate eyes. One colony of Staphylococcus species was isolated on an anaerobic blood agar plate on day 3. A single colony of Propionibacterium acnes grew on an anaerobic blood agar plate on day 6. Alpha-hemolytic streptococci grew from thioglycolate broth on day 10. CONCLUSIONS: Growth as detected in this study might represent contaminating rather than an infecting organism in an eye suspected of having endophthalmitis.

Adult↗
PubMed1995

Plasmapheresis treatment of central retinal vein occlusion in a young adult.

PURPOSE/METHODS: A 16-year-old girl with mixed connective tissue disease had central retinal vein occlusion. The patient was treated with plasmapheresis. RESULTS/CONCLUSION: Resolution of clinical findings of central retinal vein occlusion was documented by fluorescein angiography and visual field tests within 15 days of treatment. Plasmapheresis may be effective therapy in carefully selected cases of central retinal vein occlusion in young adults.

Adolescent↗
PubMed1994

Concurrent endophthalmitis and retinal detachment.

PURPOSE: Eyes with concurrent endophthalmitis and retinal detachment usually have a poor anatomic and visual outcome after treatment. The purpose of this study is to define the relation among the causative organism, the results of retinal detachment repair, and the final visual acuity. METHODS: Data were retrieved by a retrospective, computer-assisted review of the coded inpatient diagnoses from April 1987 through March 1992. RESULTS: This study included 16 patients (9 males, 7 females) ranging in age from 5 to 88 years (average, 58.7 years). Endophthalmitis was classified as exogenous in 13 (81%) patients and endogenous in 3 (19%). Two groups were identified: a virulent group that included eight (50%) patients (Staphylococcus aureus, streptococci, gram-negative, Bacillus), and a less-virulent group that included eight (50%) patients (Staphylococcus epidermidis, Propionibacterium acnes, fungal). The initial surgical procedure consisted of diagnostic vitreous fluid collection by pars plana vitrectomy (11 cases), anterior vitrectomy (1 case), or vitreous aspiration (4 cases). Additional initial adjunctive surgical procedures included pars plana lensectomy (2 cases), scleral buckling (6 cases), fluid-gas exchange (7 cases), and intraocular antibiotic injections (9 cases). In six (75%) of eight patients with endophthalmitis in the virulent group, the retina remained detached. However, in seven (88%) of eight patients with endophthalmitis in the less-virulent group, the retina remained reattached postoperatively, and the remaining patient had a stable, nonprogressive peripheral tractional retinal detachment. None of the eight patients with endophthalmitis in the virulent group retained a postoperative visual acuity of better than 3/200, and four (50%) lost all light perception. Five (62%) of the eight patients with endophthalmitis in the less-virulent group retained a postoperative visual acuity of 5/200 or better, and none lost all light perception. CONCLUSIONS: Concurrent endophthalmitis and retinal detachment patients with virulent organisms have a poor prognosis. Visual and anatomic outcomes were better in the less-virulent group.

Adolescent↗
PubMed1993

Combined extracapsular cataract extraction, posterior chamber intraocular lens implantation, and pars plana vitrectomy.

The surgical management of coexisting cataract and vitreoretinal disease has been controversial, particularly for eyes with a history of proliferative diabetic retinopathy (PDR) or chronic uveitis. We retrospectively studied the results of combined extracapsular cataract extraction (ECCE), posterior chamber intraocular lens (PC-IOL) implantation, and pars plana vitrectomy in 20 eyes of 16 patients. The indications for combined vitrectomy included dense, nonclearing vitreous hemorrhage attributed to PDR in 10 eyes, age-related macular degeneration in 2, and trauma in 1. The remaining 7 eyes had pars plana vitrectomy to remove inflammatory vitreous cell and debris associated with chronic uveitis. Follow up ranged from 4 to 32 months (average, 17.4 months). Visual acuity improved in 19 eyes (95%)--to 20/100 or better in 12 (60%). The improvement ranged from 1 to 13 Snellen lines (average, 4.9 lines). Postoperative visual acuity improvement averaged 7.5 Snellen lines for eyes with chronic uveitis, 7.0 lines for those with age-related macular degeneration, and 3.3 lines for those with a history of PDR. Postoperative visual acuity was less than 20/100 in 8 eyes (40%). In most cases, these latter results were attributed to macular changes associated with the underlying ocular disease. Our results confirm previous studies that have shown that combined ECCE/PC-IOL implantation and pars plana vitrectomy is a well-tolerated surgical procedure for diabetics, which can provide clear anterior and posterior segment media. In addition, our results suggest that this combined procedure can be useful in restoring vision in certain eyes with uveitis in the short-term postoperative period.

Adult↗
PubMed1992

Effects of subacute pyridostigmine administration on mammalian skeletal muscle function.

The subacute effects of pyridostigmine bromide were investigated on the contractile properties of rat extensor digitorum longus (EDL) and diaphragm muscles. The cholinesterase inhibitor was delivered via subcutaneously implanted osmotic minipumps (Alzet) at 9 micrograms h-1 (low dose) or 60 micrograms h-1 (high dose). Animals receiving high-dose pyridostigmine pumps exhibited marked alterations in muscle properties within the first day of exposure that persisted for the remaining 13 days. With 0.1 Hz stimulation, EDL twitch tensions of treated animals were elevated relative to control. Repetitive stimulation at frequencies greater than 1 Hz led a use-dependent depression in the amplitude of successive twitches during the train. Recovery from pyridostigmine was essentially complete by 1 day of withdrawal. Rats implanted with low-dose pyridostigmine pumps showed little or no alteration of in vivo twitch tensions during the entire 14 days of treatment. Diaphragm and EDL muscles excised from pyridostigmine-treated rats and tested in vitro showed no significant alterations in twitch and tetanic tensions and displayed the same sensitivity as muscles of control animals to subsequent pyridostigmine exposures. In the presence of atropine, subacutely administered pyridostigmine protected rats from two LD50 doses of the irreversible cholinesterase inhibitor, soman. In the absence of atropine, the LD50 of soman was not altered by subacute pyridostigmine treatment.

Acetylcholinesterase↗
PubMed1992

Extracapsular cataract extraction and posterior chamber intraocular lens implantation in uveitis patients.

PURPOSE: Intraocular lens implantation in uveitis patients has been a controversial issue. The purpose of this study is to evaluate the visual and surgical outcomes of extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (PC IOL) implantation in a diverse group of uveitis patients. PATIENTS AND METHODS: The results of 39 cases of ECCE and PC IOL implantation in 30 patients with uveitis were retrospectively analyzed. Five patients (six eyes) had pars plana vitrectomies combined with ECCE and PC IOL implantation. Patient age ranged from 26 to 71 years (average, 53.0 years). Specific uveitic syndromes were determined for 22 patients (73.3%). The postoperative follow-up period ranged from 6 to 43 months (average, 20.3 months). RESULTS: Visual acuity improved postoperatively in 38 eyes (97.4%), and this improvement ranged from 1 to 11 Snellen lines (average, 7.5 Snellen lines). Visual acuity improved postoperatively to 20/40 or better in 32 eyes (82%). Seven eyes had visual acuity worse than 20/40, which was attributed to posterior segment abnormalities after ECCE and PC IOL implantation. Uveitis recurred in 20 eyes (51.3%), and postoperative cystoid macular edema (CME) was observed in 18 eyes (46.2%). In all cases, the recurrent uveitis and CME improved or resolved with corticosteroid therapy. CONCLUSION: These results suggest selected uveitis patients can have improved vision without unacceptable risk for 1 to 3 years after ECCE and PC IOL implantation.

Adult↗
PubMed1991

Acute multifocal inner retinitis.

Two patients developed acute changes in vision two to four weeks after a febrile illness. On ophthalmic examination, each patient had bilateral vitreitis without anterior segment inflammation and multiple, bilateral, round, yellow-white inner retinal lesions that were located in the posterior pole and midperiphery. Laboratory tests did not contribute to a diagnosis. Symptomatic visual loss was caused by neuroretinitis and serous retinal detachment in one patient and by an occluded branch retinal artery in the other. The multifocal retinal lesions resolved gradually without treatment over several months with minimal or no residual retinal changes. Acute multifocal inner retinal lesions may be associated with a preceding nonspecific viral illness and may cause a sudden change in vision if associated with neuroretinitis, serous retinal detachment, or retinal vessel occlusion. We have termed this constellation of ophthalmic findings acute multifocal inner retinitis.

Acute Disease↗
PubMed1991

Presumed Pneumocystis carinii choroiditis. Unifocal presentation, regression with intravenous pentamidine, and choroiditis recurrence.

Pneumocystis carinii choroiditis is a well-documented but rare infection that has been described as a bilateral, multifocal process. Treatment efficacy has not been well established. In this report, three cases of presumed P. carinii choroiditis that developed during aerosolized pentamidine therapy for the prophylaxis of P. carinii pneumonia are described. All patients had unilateral choroiditis, and two patients were first observed to have unifocal choroiditis. In all patients, choroidal lesions decreased in size with intravenous pentamidine treatment. Choroiditis exacerbated in the two unifocal cases after the frequency of maintenance intravenous pentamidine therapy was decreased. P. carinii choroiditis may appear as a unifocal, unilateral lesion that may represent an earlier stage of infection than previously described. Intravenous pentamidine therapy appears to control P. carinii choroiditis but may need to be continued to prevent exacerbation. Patients receiving prophylactic aerosolized pentamidine therapy are not protected against extrapulmonary disease, and presumed P. carinii choroiditis may serve as a marker for disseminated infection.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Respiratory and cardiovascular effects of tetrodotoxin in urethane-anesthetized guinea pigs.

Cardiorespiratory effects of tetrodotoxin (TTX) (15 micrograms/kg, i.p.) were investigated in urethane-anesthetized guinea pigs acutely instrumented for the recording of medullary respiratory-related units (RRUs), diaphragm electromyogram (DEMG), electrocorticogram (ECoG), electrocardiogram (ECG), blood pressure (BP), endtidal CO2, and arterial O2 and CO2. Respiratory system responses showed a hyperventilatory profile during the initial stage of intoxication. This was followed by an abrupt onset of a progressive decrease in the respiratory frequency, and a respiratory rate depression-related respiratory failure. The average time to TTX-induced respiratory arrest and death was 10.3 +/- 4.2 min. Concurrently recorded inspiratory and expiratory RRU activities indicated that respiration invariably failed in an end-expiratory position as manifested by a sustained period of expiratory RRU discharge. The progressive rate depression prior to respiratory arrest was temporally correlated only to a concomitantly augmenting expiratory RRU discharge duration. Inspiratory RRU discharge duration, on the other hand, did not display any significant change throughout the course of intoxication. The asymmetry in RRU response patterns indicates either an expiratory network component's particular sensitivity to perturbation by TTX or a dissociative trend in some bulbar respiratory rhythmogenic mechanisms. Peripheral cardiorespiratory changes were also quite profound. These included a gradual and steadfast decline in BP, a steadily decreasing amplitude in DEMG oscillations, and a state of progressive hypercapnia and hypoxemia. Changes in heart rate and ECG waveform attributes prior to respiratory arrest were not appreciable. In conclusion, in addition to a variety of TTX-induced peripheral cardiorespiratory effects, findings from this study have revealed a central respiratory system component that appears to show an unusual sensitivity to perturbation by TTX. The significance of this unique phenomenon as it relates to the nature and extent of TTX-induced central respiratory depression is discussed.

Anesthesia, General↗
PubMed1990

Neurophysiological concomitants of soman-induced respiratory depression in awake, behaving guinea pigs.

Soman-induced respiratory failure was investigated in awake, behaving guinea pigs chronically instrumented to allow concurrent recordings of medullary respiratory-related unit (RRU) activity, diaphragm electromyogram (DEMG), and electrocorticogram. Responses to soman typically began with hyperpnea. Loss of consciousness, as indicated by the development of seizure activities, took place shortly after the onset of hyperpnea. This was followed by dyspnea, hypopnea, and finally, respiratory failure. The most profound respiratory dysfunctions were seen during the development of dyspnea characterized by a progressively degenerative RRU-DEMG phase relationship (phase anomalies) and mixed patterns of ataxic breathing. Electrophysiographic records indicated that the anomalous RRU-DEMG phase phenomenon is attributable to a state of functional dissociation in some brainstem mechanisms that are normally involved in the orchestration of a synchronous respiratory drive. The failure of bulbar rhythmogenic mechanisms to maintain an orderly and synchronous recruitment of respiratory drive, which led to untimely and chaotic activations of respiratory muscles, was apparently the underlying cause of various ataxic breathing patterns and a reduced ventilatory efficiency. Spectral analyses of DEMG activities showed that, despite episodic muscle fasciculations and signs of fatigue, the functional integrity of the diaphragm was not significantly compromised by soman at a dose sufficient to produce respiratory failure. These findings not only support the notion of a relatively more important involvement of central respiratory mechanisms in soman-induced respiratory failure, but also identify a state of functional dissociation of central respiratory timing mechanisms as being a significant component in soman intoxication.

Animals↗
PubMed1989

Freeze fracture analysis of the axolemma of cultured dorsal root ganglion neurons in the absence of Schwann cells.

The distribution of intramembranous particles within the axolemma of cultured dorsal root ganglion neurons was determined by freeze-fracture microscopy. Utilizing culture conditions which eliminate Schwann cells, the particle distribution of the P-face, 735 +/- 119 microns2, and E-face, 100 +/- 39 microns2 resembled that of pre- and non-myelinated axons in vivo and no node-like E-face particle patching was seen. These results indicate that cultured neurite development is similar to that seen in vivo and that axons maintained in a glial-free environment do not develop nodal, E-face membrane specializations.

Animals↗