PubMed Health⌕ Search

Biomedical subjects

W Wetzel

Publications and source records attributed to W Wetzel.

At least 55 records · Page 3Linked to original sources
PubMed1993

Laser sclerostomy ab externo using mid infrared lasers.

An ab externo fistulizing procedure (sclerostomy) was performed in vivo in 48 rabbit eyes using a pulsed (20 microseconds and 200 microseconds) Holmium:YAG (Ho:YAG) laser (2120 nm) and a pulsed (200 microseconds) Erbium:YAG (Er:YAG) laser (2940 nm). The laser energy was delivered via an infrared transmitting fiber in contact with the sclera, with the fiber inserted into a specially sharpened retractable cannula in order to guide it into the subconjunctival space. An additional optical fiber-fiber coupling system was required for the Er-YAG laser. A patent fistula (200-micrometers diameter) with formation of a filtering bleb and marked intraocular pressure reduction was achieved in nearly all cases. Significant intraoperative or postoperative complications occurred only with the 20-microsecond Ho:YAG laser. Trauma to the conjunctiva was as minimal as in a subconjunctival injection. The Er:YAG laser created a smaller thermal damage zone at the fistula walls and required significantly less laser energy than the Ho-YAG laser.

Animals↗
PubMed1992

Local heat and cold application after eastern cottonmouth moccasin (Agkistrodon piscivorus) envenomation in the rat: effect on tissue injury.

We studied the effect of local application of heat or cold on the development of tissue necrosis in envenomated rats. Anesthetized animals had 6 mg/kg venom from Agkistrodon piscivorus injected subcutaneously into the lateral aspect of a hind limb. Heat or cold was applied to the site of envenomation in the experimental groups for 4-6 hr, and the injected area was examined histologically after 24 hr. Neither local treatment, with or without the presence of systemic antivenin, significantly affected the severity of tissue necrosis induced by the venom in comparison to a control group left at ambient temperature.

Animals↗
PubMed1991

[Relevance of ocular pressure tonometry and classical tonometry with reference to prognosis in suspected glaucoma and ocular hypertension].

A total of 44 eyes of patients with suspected glaucoma or ocular hypertension were examined both by ocular pressure tonometry (OPT) according to Ulrich and by tonography according to Leydhecker. The visual fields of these eyes were prospectively followed up for 3 years to compare the prognostic value of the two methods. In 30 of the 44 eyes a worsening visual field loss was observed, while in 14 the visual fields showed no change. Much better correlation was noted between values obtained by OPT and changes in visual field than between values obtained by tonography and visual field loss. Conventional tonography yielded 39% of false-negative values, but only 11% were recorded with OPT. Therefore, according to results of these and further investigations, OPT appears to be a more helpful and reliable method for assessment and decisions on therapy in patients with suspected glaucoma or ocular hypertension.

Humans↗
PubMed1990

Paradoxical sleep-promoting effects of brain extract from paradoxical sleep-deprived rats.

Brain extract was obtained from whole brains of donor rats following four days of paradoxical sleep deprivation (PSD). Intraperitoneal injection of this brain extract in normal (i.e., not pretreated) recipient rats led to a significant increase of paradoxical sleep (PS) which was beginning at the third hour postinjection and still present on the day after treatment. Both PS episode number and PS episode duration were increased by the PSD extract, whereas slow-wave sleep was not influenced. Brain extract of nondeprived control rats, on the other hand, had no significant effects. In the present experiments, an extract volume obtained from two donor brains was transferred to one recipient. Compared to our earlier investigations (one donor brain/one recipient) this higher "dose" of PSD extract exerted a more pronounced and prolonged effect. These results support the idea that some PS-inducing factor(s) accumulating in the brain during PS deprivation may be involved in the regulation of paradoxical sleep.

Animals↗
PubMed1990

[Results of scanning electron microscopy following internal laser sclerostomy].

An experimental glaucoma-filtering procedure ab interno, laser sclerostomy, can be performed using the argon and Q-switched Nd:YAG laser. Compared with surgical techniques the advantages of laser sclerostomy are: minor trauma to the conjunctiva and no risk of infection. In this study 28 rabbit eyes were examined by histological techniques and by scanning electron microscopy 2 days or 4 months following laser sclerostomy. The internal fistular ostium as well as the scleral tunnel showed a relatively smooth margin. Two days after laser sclerostomy, endothelial cell damage was found in only a small area directly surrounding the internal ostium; 4 months later all of this damage was repaired.

Animals↗
PubMed1990

Effect of repeated application of nootropic drugs on sleep in rats.

The effects of repeated application of nootropic drugs on the sleep-wake cycle were investigated in rats. Piracetam, meclofenoxate and pyritinol were injected intraperitoneally, 100 mg/kg per day, during a period of 10 days. The sleep-wake cycle was recorded each day between 8 a.m. and 4 p.m. Repeated administration of piracetam and meclofenoxate led to an increase of the paradoxical sleep, a decrease of waking, and a very small increase of slow-wave sleep. Pyritinol, on the other hand, decreased the amount of paradoxical sleep. The paradoxical sleep latency was reduced by piracetam and meclofenoxate and enhanced by pyritinol, respectively. These findings and also previous results show that nootropic drugs have different effects on sleep, especially on paradoxical sleep. The possible relationship between sleep effects and memory effects of nootropic drugs and the usefulness of sleep studies for screening of nootropics are discussed.

Animals↗
PubMed1990

[Lens position following planned capsular sac fixation: results of 200 consecutively surgically treated phacoemulsifications].

A total of 200 phacoemulsifications with planned in-the-bag fixation of one piece PMMA posterior chamber lenses implanted consecutively by one surgeon were examined on postoperative days 3-7. Special attention was given to both position of the haptics and centering of the lens. No sodium hyaluronate or other viscoelastic materials were used in any of the operated eyes. After capsulorhexis and phacoemulsification inside the bag we were able to confirm in-the-bag fixation in 190 implants (95%). In 197 of the 200 patients centering of the IOL was excellent. The capsular rim of the circular capsulorhexis was preserved in all cases due to phacoemulsification within the capsular bag. This procedure meets the best conditions for a secure in-the-bag insertion of the posterior chamber lens. Expression of the lens nucleus after capsulorhexis or through the so-called letter-box technique leads to a remarkably lower percentage of proven bag-bag fixation of the haptics.

Cataract Extraction↗
PubMed1989

[Laser sclerostomy: an alternative to current surgical filtering procedures. Experimental studies].

A new filtering procedure, laser sclerostomy, was performed in 12 rabbit eyes by combined application of an argon and a YAG laser. In 10 cases an open fistula connecting the anterior chamber and the subconjunctival space could be demonstrated histologically. As neither the conjunctiva nor the globe are incised "ab externo," the possibility of an intraoperative infection is excluded and the risk of postoperative scar formation is minimized. Consequently, laser sclerostomy promises a new approach to glaucoma control in human eyes, too.

Animals↗
PubMed1989

[Ocular outflow resistance and rate of secretion of aqueous humor following iridotomy and posterior capsulotomy with the Nd:YAG laser].

When the Nd:YAG laser is used for iridotomy and posterior capsulotomy an elevation in the intraocular pressure (IOP) is often found within the first few postoperative hours and in some cases for even 1-3 days. In 39 eyes the changes in postoperative intraocular pressure were noted and the preoperative as well as the postoperative outflow facility and aqueous secretion flow measured by oculopressiontonometry. The results demonstrated that in both iridotomy and posterior capsulotomy a reduction in the outflow facility caused the postoperative rise in IOP. Aqueous secretion flow did not increase. Most iridotomy patients had glaucoma and consequently reduced preoperative outflow facility. This determined the postoperative IOP elevation. In capsulotomy patients, no such correlation was evident, but the role of the laser energy applied seems to be more important according to our results.

Aqueous Humor↗
PubMed1988

[Are alcoholic polyneuropathies reversible?].

Polyneuropathies by long term alcohol dependent patients are characterized by symmetric distal type of manifestation. By abstinence we found a diminution of symptoms. It is a point of view for treatment and diagnostic.

Adult↗
PubMed1987

Supplemental dietary tyrosine in sepsis and acute hemorrhagic shock.

Previous studies showed that dopamine and norepinephrine levels in rat brain are reduced following stress and that rats fed supplemental tyrosine do not exhibit these reductions. We hypothesized that dietary supplementation with tyrosine would enhance resistance to acute hemorrhagic shock and sepsis by increasing substrate (tyrosine) availability for catecholamine synthesis. Rats were fed either a standard rat chow (6.8 g of tyrosine per kilogram of chow), which supports normal growth, fertility, and longevity, or the same chow supplemented with 10 g of tyrosine per kilogram of chow. Seven days later, the rats underwent cecal ligation and perforation while under intraperitoneal pentobarbital anesthesia. There was a significant increase in survival in the tyrosine-supplemented group. Similarly, in another experiment, tyrosine-supplemented rats were able to tolerate acute fulminant hemorrhagic shock better than were nonsupplemented control animals.

Acute Disease↗
PubMed1985

[Radiotherapy treatment of malignant melanoma of the corneoscleral zone].

Report on a case of malignant melanoma of the limbus and the neighboring cornea and conjunctiva. Excision of the tumor was not possible because of widely scattered cells in the cornea and conjunctiva. After evident progression of the tumor was observed, with signs of inflammation and prominence, radiotherapy was decided on. The melanotic area was irradiated with the strontium 90 applicator, with altogether 65 Gy. The central tumor region in the limbus was saturated with altogether 105 Gy. Four years later residual pigment cells were found in the limbus and the neighboring cornea and conjunctiva, without any signs of recurrence.

Aged↗
PubMed1985

Effects of nootropic drugs on the sleep-waking pattern of the rat.

The effect of nootropic drugs on sleep-walking pattern was investigated in adult male Wistar rats. Continuous polygraphic sleep recording was made 8 h per day between 8.00 a.m. and 4.00 p.m. Piracetam (100 mg/kg), meclofenoxate (100 mg/kg), pyritinol (100 mg/kg), or methylglucamine orotate (225 mg/kg) were injected intraperitoneally immediately before the onset of recording. The substance effects were compared to pre-drug and post-drug NaC1 control days. The paradoxical sleep (PS) latency was prolonged by pyritinol and methylglucamine orotate. The percentage of PS was decreased by pyritinol and methylglucamine orotate, but increased by piracetam. Pyritinol and methylglucamine orotate decreased the number of PS episodes, whereas piracetam increased the mean duration of PS episodes. Meclofenoxate had no significant effects except for an increase in the number of very long PS episodes (5 min or more). Slow wave sleep and walking were affected only in the case of pyritinol. But also pyritinol, similar to piracetam and methylglucamine orotate, seems to have selective actions on PS as shown by the PS/total sleep ratio.

Animals↗