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Biomedical subjects

G Richard

Publications and source records attributed to G Richard.

At least 181 records · Page 10Linked to original sources
PubMed1987

Effect of imipenem (N-formimidoyl-thienamycin) on the in-vitro lymphocyte proliferation.

Imipenem, a new carbapenem, was tested for its inhibitory or stimulatory effects on concanavalin A- and phytohaemagglutinin-stimulated and unstimulated proliferation (measured by 3H-thymidine uptake) of murine splenocytes and thymocytes. Addition of imipenem at concentrations of 10-50 mg/l induced lymphocyte transformation in unstimulated and mitogen-stimulated lymphocytes. Since imipenem stimulated blastogenesis at concentrations achievable in serum when used therapeutically, these results may have potential clinical significance.

Animals↗
PubMed1987

A middle ear implantable hearing device for controlled amplification of sound in the human: a preliminary report.

Millions of people in the United States suffer from hearing impairment that is not benefited or poorly benefited by surgery or conventional hearing aids. Recently, we introduced an implantable Temporal Bone Stimulator (TBS) designed for those patients having a hearing loss due to external canal conditions; such as, external canal atresia or disease, inoperable ossicular problems, atelectasis or eustachian tube malfunction, and chronic open-cavity mastoid disease. This device requires relatively good cochlear function. However, the electromagnetic application of this device has led to the development of a new device we call the Implantable Hearing Device (IHD). This device stimulates, by an electromagnetic field, an independent electromagnetic sensitive prosthesis attached to the ossicular chain. This direct energy transfer to the ossicular chain provides a high degree of sound amplification and fidelity, thus providing benefit for those with various degrees of sensorineural hearing impairment. Preliminary disclosure of the device design, the animal experimental results, and the data from human testing will be given.

Animals↗
PubMed1986

Treating avulsed vessels with a temporary balloon buckle.

We treated nine patients with avulsed retinal vessels by first expanding a balloon in the parabulbar space to buckle the vessel temporarily and then applying a laser beam to the avulsed segment. In three patients the avulsed vessel was an artery and in six it was a vein. The avulsion was the only abnormality in three patients; in six it was combined with a retinal break, which was accompanied by a detachment in five. The balloon brought the avulsed portion of the vessel into contact with the retina and the pigment epithelium and made it receptive to laser coagulation. Flow in the vessel could be slowed or stopped while the patient was undergoing laser treatment by further expanding the balloon.

Evaluation Studies as Topic↗
PubMed1986

The treatment of difficult retinal detachments with an expanding gas bubble without vitrectomy.

In a prospective study on the use of perfluorocarbon gases (CF4, C2F6, C3F8) without prior mechanical vitrectomy, 51 retinal detachments that were not suitable for scleral buckling were treated by injection of a small bubble of gas into the vitreous to form a tamponade. There were 23 patients with giant tears, 16 with posterior holes, 9 with breaks at different latitudes, and 3 in whom the gas was used for diagnostic purposes. The gases were sustained at therapeutic volumes for 10-70 days. The tears were sealed with argon or krypton laser. The overall reattachment rate was 71%. Postoperative visual acuity improved or remained the same in all patients with reattached retina. In a follow-up of 1 year-38 months there were no late complications, such as cataract, glaucoma, keratopathy, or subsequent visual deterioration.

Adolescent↗
PubMed1986

An implantable hearing device: osseointegration of a titanium-magnet temporal bone stimulator.

The use of bone conduction hearing devices has recently entered the realm of implantable prostheses and solid-state electronics, resulting in improved fidelity and applicability for a wider range of patients. One particular device, a temporal bone stimulator (TBS), consists of an external sound processor and implanted portion to cause vibration under the skin. An implantable temporal bone stimulator screw constructed of titanium alloy with a permanent magnet can be vibrated by inductive transcutaneous coupling. The safety and osseointegration of the TBS bone screw were tested in adult goats that were free-field stimulated at 75 dB with the TBS processor for 4 to 21 weeks. Histologic comparisons of the soft tissue and bone adjacent to active and passive screws revealed no remarkable differences between them with bone growing in the interstices of the threaded portion. Evidence for mild reorganization of bone was shown with Goldner's stain, which differentiated bone that was young and unmineralized from bone that was older and mineralized. Reorganization was evident in both the active and passive sites and there was no remarkable difference between the two in a blind study. Additional evidence for the integrity of the implant was obtained by subjecting a calvarium containing both screws to a 5000 gauss magnetic field for 10 minutes of a nuclear magnetic resonance head scan. The calvarium was first dissected free from overlying skin and connective tissue. The magnet-containing screws were not loosened. We conclude that the implanted screw portion of the TBS implantable hearing device is well-integrated into the temporal bone. Mild stimulation of new bone growth indicates a healthy long-term viable implant for bone conduction amplification of sound.

Animals↗
PubMed1985

[Bilateral retinal vein occlusions and general risk factors].

A report on 12 patients with retinal vein occlusion in both eyes. In addition to advanced age (67 years on the average) the following risk factors were present, often in combination: hypertension, cardiac insufficiency, adiposity, hyperlipidemia, hyperuricemia, hypercholesterinemia, diabetes mellitus etc. The rate of retinal circulation was determined by video fluorescein angiography. A pronounced decrease in visual acuity was observed in all patients with a slower retinal circulation rate. The causes of the decrease in central visual acuity were macular edema, neovascularization with vitreal hemorrhage and rubeosis iridis with secondary glaucoma.

Aged↗
PubMed1985

[Effect of laser therapy in diabetic retinopathy on the hemodynamics of retinal vessels].

Changes in retinal hemodynamics are a factor of major influence in diabetic retinopathy. With the aid of videoangiography, the changes in retinal circulation times before and after therapeutic laser coagulation were examined in a prospective study. A marked diminution of all circulation times was observed after laser coagulation procedures: the arterial circulation time decreased from 1.02 s to 0.74 s average, the early venous circulation time from 5.18 s to 3.50 s average, and the late venous circulation time from 9.07 s to 8.16 s. Laser coagulation has a more significant influence on the capillary circulation of the retina than on the venous phase. In diabetic retinopathy, the improvement in pathologic hemodynamic situations in the retina may be a very important mechanism of action in laser coagulation therapy.

Blood Flow Velocity↗
PubMed1985

[Effect of arterial blood pressure on retinal hemodynamics--a videoangiography study on the problem of autoregulation of blood supply to the retina].

In the videoangiographic study reported here the influence of blood pressure on retinal hemodynamics was investigated. Data for the study were obtained from a group of 377 patients. It was found that circulation times in the retina grow shorter as diastolic and arterial blood pressure rise. Diastolic blood pressure has a greater influence than systolic blood pressure on the circulation times in the eye. The increased velocity of retinal blood flow (as measured by the retinal circulation times) probably represents an autoregulative attempt to keep the blood supply in the retinal capillary system constant in spite of fluctuating blood pressure. When hypertensive changes in the retina or optic disk are ophthalmoscopically demonstrable, however, they are a sign that even the retinal autoregulation can no longer compensate for the effect of rising blood pressure on retinal hemodynamics: videoangiograms of this situation reveal an unmistakable slowing-down of retinal circulation, i.e., an increase in retinal circulation times.

Blood Pressure↗
PubMed1985

Suppression of cellular immunity to Listeria monocytogenes by activated macrophages: mediation by prostaglandins.

We previously demonstrated the suppression of cell-mediated immunity to Listeria monocytogenes by Pseudomonas aeruginosa-induced, macrophage-like cells. The present study was undertaken to evaluate the mechanism for this suppression. P. aeruginosa supernatant was shown to activate macrophages by the criteria of increased bactericidal capacities and increased attachment to glass surfaces. Acquired cellular resistance to L. monocytogenes could also be inhibited by macrophages from L. monocytogenes-pretreated mice. The depression of acquired immunity by P. aeruginosa- or L. monocytogenes-activated macrophages did not appear to be due to a reduction of antigenic stimulus after nonspecific macrophage activation. In contrast, our findings suggest that suppression is mediated by activated macrophages through a prostaglandin-dependent mechanism. In vivo administration of aspirin blocked the immunosuppressive effect of P. aeruginosa- or L. monocytogenes-activated cells. Moreover, the suppressive activity of supernatants of macrophages from Listeria-infected mice was reversed when indomethacin was present during supernatant generation. Finally, prostaglandin E1 treatment in vivo profoundly inhibited the induction of cell-mediated immunity to L. monocytogenes. The possible role and mechanism of prostaglandin in suppressing cellular immunity to intracellular bacteria are discussed.

Alprostadil↗
PubMed1985

[Modification of retinal hemodynamics by induced changes in intraocular pressure: a videoangiographic study].

This study used videoangiography to observe the effect of artificially produced rises in pressures in the eye on the haemodynamics of the retinal vessels. The intraocular pressure was increased with Müller's ophthalmodynamometer in stages of 10 mm Hg. A demonstrable effect upon the arterial and early venous times as well as the arm-retina time appeared. A constant rise in pressure appeared in the acute experiment: here the circulatory times more than doubled when intraocular pressure rose from under 20 mm Hg to 40 mm Hg. Above 50 mm Hg a further, statistically highly significant increase in the circulatory times of the eye became evident. The retinal vessels were obliterated in the rule at intraocular pressures above 50 mm Hg. When the data on changes in retinal circulation acquired by videoangiography are compared with the data on blood volume flow-through reached with microspheres, both methods reveal a good correlation. This shows that the determination of circulatory times in the eye is also a source of information on blood volume flow.

Adult↗
PubMed1985

Clinical observations concerning choroidal folds.

This paper deals with 6 patients who suffer from choroidal folds. Special emphasis will be laid on several aspects of differential diagnostics. In our 6 cases discussed here, we found a retrobulbar tumor in 3 patients, hypotony in 1, and a marked hyperopia in another as causes. In the 6th patient no pathological condition was found, and, therefore, we characterized the choroidal folds in this case as idiopathic.

Aged↗
PubMed1985

[Changes in retinal hemodynamics in old age].

The influence of increasing age on the haemodynamics of the retina was examined in a prospective study using 377 consecutive videoangiograms. A significant alteration of the arm-to-retina time and the arterial, capillary and venous phases of the retinal circulation is not detectable before the 60th year of life. After the age of 60 all circulation times change in a negative sense. A further, pronounced slowing of retinal circulation appears after the 75th year of life. This shows that the well-known morphological alterations in the retinal vessels in old age are accompanied by haemodynamic changes.

Adult↗
PubMed1985

[Lymphoscintigraphy. A predictive test of post-traumatic lymphedema of the lower limbs].

Post-traumatic oedema after fractures of the tibia results from several causes which are often associated together. In addition to venous thrombosis, the lymphatic origin of oedema is not inconsiderable. Lymphatic scintigraphy was performed in 32 patients with tibial fractures, either open or closed. All were fixed internally. All had preventive treatment of venous thrombosis by calciparin. The intact leg was also investigated by scintigraphy which was done two to ten days after the trauma. The possible anomalies of scintigraphy are described and discussed. The patients were divided into two groups. Group one developed oedema at three months and group two did not. The anomalies of scintigraphy were significantly higher in group one. It is concluded that early scintigraphy is a safe test for the prediction of residual oedema after tibial fractures. The possible early prevention of oedema of a lymphatic origin is discussed.

Adult↗
PubMed1984

[Use of videoangiography of the retina].

A system is presented with the help of which high-quality visual presentation of fluorescein angiographies is possible. The individual elements of the unit are described (TV camera, light source, adapter for the TV camera, fundus camera, video recorder, video timer). The filming process is less strenuous for the patient than serial angiography since he is no longer dazzled by high-intensity light. The pictures are available immediately after filming, thus eliminating both the cost of developing and the delay involved. The examiner can make picture adjustments during filming. The high degree of resolution of this examination method in proportion to the time required for it makes a precise analysis for the physiological and pathological hemodynamics of the retinal- and choroidal blood vessels possible.

Fluorescein Angiography↗