Biomedical subjects

W Wetzel

Publications and source records attributed to W Wetzel.

At least 37 records · Page 2Linked to original sources

PubMed1995

Open field behaviour in rats: role of metabotropic glutamate receptors.

Previous studies have shown that spatial memory retention is affected by the metabotropic glutamate receptor (mGluR) influencing agents (R,S)-alpha-methyl-4-carboxyphenylglycine (MCPG) and trans-azetidine-2,4-dicarboxylic acid (tADA). In the present investigation we examined whether the mGluR antagonist MCPG (20 mM and 200 mM/5 microliters, respectively) and the agonist tADA (20 mM/5 microliters) have other behavioural effects using the open field test on two successive days. Only minor effects of MCPG (decrease of crossings during the 1st min on day 1) and tADA (increase of rearings on both days) were found. These results suggest that memory influencing doses of MCPG and tADA have no or only little behavioural effects in the open field situation.

Animals↗

PubMed1995

Block of spatial learning by mGluR agonist tADA in rats.

As demonstrated recently, mGluRs are involved in some forms of learning. We thus investigated the effect of tADA (trans-azetidine-2,4-dicarboxylic acid) applied intracerebroventricularly prior to learning a spatial alternation paradigm. Compared to controls, tADA treated animals were amnesic when tested for retention 24 hr after training. Effects of state-dependency were excluded. These data and our earlier work indicate that both mGluR agonists and antagonists can have memory-disrupting effects.

Animals↗

PubMed1995

Development of a new Er: YAG laser conception for laser sclerostomy ab externo: experimental and first clinical results.

The erbium:YAG laser is a preferable energy source for laser sclerostomy ab externo due to the high absorption of its radiation (2940-nm wavelength) in the aqueous parts of scleral tissue. It has thus far been a disadvantage that laser energy has to be transmitted from the laser source to the application site via very susceptible special optical fibers (ZrF). As a consequence of technical improvements, the laser source could be integrated into the application probe. Therefore, only a robust quartz fiber was necessary for contact application. A fiber diameter of 400 microns was chosen according to the experience gained in previous studies. A total of 24 eyes with chronical open-angle glaucoma were treated. A fistula end-point detection unit was developed for safe indication of a full-thickness perforation of the sclera. With a fiber diameter of 400 microns, a postoperative success rate of about 54% was achieved at 6 months follow-up. The automated full-thickness perforation detection prevented the application of additional, surplus laser pulses in the anterior chamber. The postoperative success rate could be improved over that achieved in previous studies. The new device/conception offers more technical reliability and is a further step toward minimally invasive fistulating laser surgery of open-angle glaucoma.

Erbium↗

PubMed1995

[Progress in laser sclerotomy ab externo] Enlarging the sclerostomy channel and local mitomycin administration].

In a previous study we presented our first results after sclerostomy using a pulsed erbium/holmium: YAG laser. At a fiber diameter of 300 microns a success rate of 20-30% was found after a 1-year follow-up. This study concentrates on the improvement of the parameters for filter survival. METHODS. The fiber diameter and thus the size of the fistula increased to 400 microns. Patients who had undergone fibrosis for a previous fistula were treated intraoperatively with topical mitomycin administration. RESULTS. After a follow-up of 6 months, filter function in the 300 microns group was maintained in 26% of the treated eyes (n = 23), while 400 microns fistulas were successful in 48% (n = 26). In the mitomycin-treated group (n = 6), sclerostomy achieved an IOP regulation in four patients. Postoperative hypotony was more frequent, but did not exceed 2 weeks. CONCLUSION. An increase in fistula diameter improves the long-term results of laser sclerostomy. Mitomycin is useful in maintaining filter function in patients with an unfavorable prognosis.

Antibiotics, Antineoplastic↗

PubMed1995

Gastric syphilis: endoscopic and histological features mimicking lymphoma.

The United States is currently experiencing a syphilis epidemic. We report three cases of gastric syphilis seen during a 1-yr period. These cases were endoscopically and microscopically confused with lymphoma. Recent evidence has suggested that Helicobacter pylori has a causative role in the development of gastric carcinoma, lymphocytic gastritis, and lymphoma, as well as peptic ulcer disease and chronic gastritis. During the same period of heightened awareness for the role of H. pylori-associated gastric pathology, there has been a simultaneous rise in the incidence of syphilis throughout the United States, especially in the inner city. Gastroenterologists and pathologists must have an awareness that gastric syphilis can mimic lymphocytic gastritis and gastric lymphoma. Because of the current syphilis epidemic, gastric syphilis must be carefully considered as a diagnostic possibility in any patient with endoscopic and histological findings suggesting lymphocytic gastritis or lymphoma. This diagnosis of gastric syphilis should be weighed even when H. pylori infection is present. All three of our patients tested negative for the HIV antibody.

Adult↗

PubMed1995

Laser sclerostomy ab externo using two different infrared lasers: a clinical comparison.

This study was designed to compare the clinical results of an ab externo approach to laser sclerostomy using two different laser sources under identical conditions. A pulsed (200 microseconds) erbium-YAG laser (lambda = 2940 nm) and a pulsed (200 microseconds) holmium:YAG laser (lambda = 2120 nm) were used. The energy of each laser was transmitted via a fiber (300 microns in diameter) and applied near the limbus, with the fiber tip remaining in steady contact with the sclera. According to the higher tissue absorption coefficient, a shorter penetration depth and, therefore, fewer complications were expected for the Er:YAG laser. A total of 26 patients with advanced open-angle glaucoma were treated and followed for up to 6 months. In all cases a functioning fistula with a prominent filtering bleb and a marked reduction in the intraocular pressure (from up to 35 mm Hg to < 10 mm Hg) could be achieved primarily. The total energy required was about 4 times lower for erbium:YAG laser was compared with holmium:YAG laser sclerostomies. No complication occurred intraoperatively. Postoperatively, reversible adherence of the iris to the internal ostium was more frequently observed in Ho:YAG laser sclerostomies (60%) and small hyphemas were more often seen in Er:YAG laser sclerostomies (30%). After 6 months of follow-up, about 40% of the fistula remained patent in both groups. In principle, both lasers are suited to serve as energy sources for the described approach. Under the conditions of the present study, different levels of thermal effects did not cause any significant difference in the clinical success rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Transition to parenthood. What about fathers?

Family physicians are in a strategic position to help couples adjust to the many changes that occur during the transition to parenthood. We review some of the issues for fathers at this time and suggest strategies for family physicians for including fathers and assisting couples to adjust to the changes in the interest of promoting healthy families.

Adaptation, Psychological↗

PubMed1994

Computer-assisted shock-reinforced Y-maze training: a method for studying spatial alternation behaviour.

Y-mazes are widely used for discrimination learning and spatial alternation tasks. We present here a computer-assisted Y-maze model for spatial alternation learning via footshock reinforcement. No intramaze cues are provided and handling between trials is no longer required. Pretraining application of scopolamine (1 mg kg-1) and D-AP5 (2-amino-5-phosphonopentanoate; 0.016 mg) clearly impairs acquisition and retention (tested 24 h after acquisition) of spatial alternation. These effects are not due to state-dependent changes caused by drug treatment. Similar results were reported by others in food-motivated spatial alternation tasks as well as spontaneous alternation paradigms. The data support our model as a useful tool for studying spatial alternation in the Y-maze.

2-Amino-5-phosphonovalerate↗

PubMed1994

(R,S)-alpha-methyl-4-carboxyphenylglycine (MCPG) blocks spatial learning in rats and long-term potentiation in the dentate gyrus in vivo.

Recently, it was demonstrated by the use of the competitive and selective antagonist (R,S)-alpha-methyl-4-carboxyphenylglycine (MCPG) that metabotropic glutamate receptor (mGluR) activation is required to induce long-term potentiation (LTP) in the hippocampus. Accordingly, we investigated whether MCPG also inhibits spatial learning. Rats were trained on a spatial alternation task in a Y-maze with footshock reinforcement, and MCPG (0.0208 mg) was injected intracerebroventricularly prior to training and/or retention test. Animals injected pre-training are clearly impaired in retention, whereas preretention application was without effect. A state dependency could be excluded. Additionally, MCPG at the same concentration completely blocks a potentiation at perforant path/dentate gyrus synapses in vivo. These results strongly implicate a role of mGluRs in spatial learning and LTP.

Animals↗

PubMed1994

Laser sclerostomy ab interno using continuous wave and pulsed lasers in a rabbit model.

PURPOSE: This experimental study was designed to find an optimal combination of parameters for a gonioscopic ab interno approach to laser sclerostomy. METHODS: Laser sclerostomy ab interno was performed delivering the laser energy via a slit lamp and a gonioscopic contact lens to the iridocorneal angle. The laser energy is required to be well transmitted by the cornea and at the same time to be maximally absorbed by the sclera at the iridocorneal angle. For local enhancement of absorption the sclera was stained with the biocompatible dyes Fluorescein (absorption maximum at 480 nm) and Methylene blue (absorption maximum at 668 nm) applied by iontophoresis. A continuous-wave (cw)-Argon laser and a cw-dye laser produced relatively long pulses (200 ms) at wavelengths matching with these respective maxima. Additionally a pulsed dye laser emitting shorter pulses (2 microseconds) was successively adapted to the wavelengths of the two maxima. In some cases a Q-switched Nd: YAG laser had to be used for perforation of Descemet's membrane. A total of 44 rabbit eyes was treated to compare the results for these four different laser/dye combinations. RESULTS: While no successfull perforation of the sclera could be achieved using the cw-dye laser with scleral staining by Methylene blue, the intraoperative success rate ranged between 59% and 75% for the other three laser/dye combinations. Histological examinations of the eyes on the first postoperative day showed smaller thermal necrosis zones, but more often fibrin reactions when using the shorter pulse length. Although we often found iris adherences to the internal fistula ostium, no major complications were observed. CONCLUSION: Further improvement of intraoperative success rates is needed, before clinical application of the approach can be considered.

Animals↗

PubMed1994

Effects of CLIP (corticotropin-like intermediate lobe peptide) and CLIP fragments on paradoxical sleep in rats.

The effects of the POMC-derived peptide CLIP [corticotropin-like intermediate lobe peptide; ACTH(18-39)] and its shorter fragments ACTH(25-39), ACTH(18-24), and ACTH(20-24) on sleep were investigated in rats housed under normal 12-h light/12-h dark conditions (0600 light on). CLIP (10 ng) or equimolar doses of CLIP fragments, respectively, were injected intracerebroventricularly immediately before the 8-h recording period (0800-1600). It was found that paradoxical sleep (PS) was increased by CLIP (+20%) as well as by the N-terminal CLIP fragment ACTH(18-24) (+18%) and by the pentapeptide ACTH(20-24) (+25%), whereas the C-terminal fragment ACTH(25-39) was ineffective. Slow-wave sleep (SWS) was not influenced. These results clearly demonstrate that CLIP and its N-terminal fragments have selective PS-enhancing effects. CLIP and/or CLIP partial sequences are possible candidates for endogenous PS-inducing peptides involved in the physiological regulation of paradoxical sleep.

Adrenocorticotropic Hormone↗

PubMed1994

Effects of [des-Tyr-D-Phe3]beta-casomorphin (2-5) on cortical EEG power spectra in rats.

The effects of the peptide [des-Tyr-D-Phe3]beta-casomorphin(2-5) (BCH-325; Pro-D-Phe-Pro-Gly; 2.27, 22.7, and 227 micrograms/kg) on cortical EEG power spectra in rats were studied compared to those of other psychotropic drugs, including diazepam, amitriptyline, haloperidol, and amphetamine. All drugs were injected IP, and cortical EEG power spectra were recorded from freely moving rats for 2 h postinjection. Administration of 22.7 and 227 micrograms/kg BCH-325 resulted in an increase in alpha-2 and beta-1 frequency bands and a decrease in slower frequencies (delta, theta). Our findings show that the effects of BCH-325 on cortical EEG power spectra differ from those of other psychotropic drugs.

Animals↗

PubMed1994

[Complete occlusion of the capsulorhexis incision by anterior capsule shrinkage].

UNLABELLED: The capsulorhexis technique has become established as procedure of choice for anterior capsular opening in cataract surgery. With the spread of the method even relatively rare complications are gaining in importance. CASE: In a patient with cataract and multifocal chorioretinitis, phacoemulsification with implantation of a one-piece PMMA posterior chamber IOL through a capsulorhexis opening was performed without complications. Within a period of 3 months, shrinking of the anterior capsule led to complete occlusion of the anterior aperture. To our knowledge, no comparably severe finding has been reported. The anterior capsule was successfully opened by by means of Nd:YAG laser capsulotomy. However, improvement in visual acuity was limited by cystoid macular edema due to the basic condition. CONCLUSION: No relations with other systemic or eye diseases have yet been demonstrated. As another case report describes a similar--though less severe--combination of progressive constriction of the anterior capsule and inflammatory eye disease, the opening of the anterior capsule in such cases should be sufficiently large. If anterior capsular shrinkage has developed, Nd:YAG-laser capsulotomy is a low-risk method of therapy.

Aged↗

PubMed1994

Ocular aqueous humor dynamics after photodisruptive laser surgery procedures.

Iridotomy and capsulotomy using the Q-switched Nd:YAG laser affect ocular aqueous humor dynamics, causing intraocular pressure (IOP) temporarily to rise following these procedures. We measured aqueous outflow facility and aqueous secretion flow by oculopression tonometry in 20 eyes before and after YAG laser iridotomy, and in 19 eyes before and after YAG laser posterior capsulotomy. IOP increased after both laser procedures. Our measurements showed that this elevation must have been caused by a reduction in outflow facility, since aqueous secretion flow actually decreased. In the iridotomy patients, the preoperative outflow facility (in most of the cases, already compromised preoperatively by glaucoma), was directly related to the maximum postoperative IOP elevation. In the capsulotomy patients, postoperative outflow facility was correlated with the total laser energy used. No such correlation was observed in the iridotomy patients. Additionally, in the capsulotomy patients, the type of secondary cataract (ie, proliferative or fibrotic) may have influenced the level of reduction of outflow facility.

Aqueous Humor↗

PubMed1994

Genograms. Practical tools for family physicians.

A genogram can help a physician integrate a patient's family information into the medical problem-solving process for better patient care. A genogram allows a physician to obtain medical and psychosocial information from a patient easily and, as a result, to have a better understanding of the context of the presenting symptoms.

Conflict, Psychological↗

PubMed1994

Laser sclerostomy ab externo using the erbium: YAG laser. First results of a clinical study.

A new approach to fistulating glaucoma surgery, laser sclerostomy ab externo, was investigated in a clinical study. A pulsed (200 microseconds) erbium-YAG laser was used, as its wavelength (2940 nm) is very well absorbed by tissue water. The laser energy was transmitted via a fiber to an application probe with a cannula particularly designed to guide another fiber into the subconjunctival space. Nine patients with advanced open-angle or neovascular glaucoma were treated. In all cases a functioning fistula with a prominent filtering bleb and a reduction of the intraocular pressure (from up to 50 mmHg to 8-18 mmHg) could be achieved. The total energy was 60 mJ on average. No complication occurred intraoperatively. Postoperatively, all fistulas in patients with neovascular glaucoma (n = 6) were impatent after approx. 7 days due to iris adherence to the internal ostium and episcleral scarring. In cases of open-angle glaucoma (n = 3) a patent fistula persisted for several months. Variation of the exposure parameters, the use of antiproliferative drugs, and a less restrictive selection of patients could further improve the success rate.

Fiber Optic Technology↗

PubMed1993

Comparison between the flicker test procedures of Aulhorn and of Dölle in the diagnosis of optic neuritis.

The use of the flicker test for diagnostic purposes is based on the absence of Brücke's effect during acute inflammation of the optic nerve. The test device of Aulhorn was compared with another, less expensive flicker test device, that of Dölle. The flicker test device of Aulhorn uses a mechanical projection system. In the device of Dölle, the flicker field is formed by electronically controlled groups of light-emitting diodes. In an initial examination, the reliability of Aulhorn's test was slightly higher than of Dölle's procedure. The normal ranges in 45 healthy subjects differed markedly between the two methods. One hundred and fifteen eyes of patients with established or suspected optic neuritis were also examined. Although there were differences in some conditions (e.g. shape and homogeneity of flicker field) due to the techniques, the specificity and sensitivity of the two methods were similar concerning the diagnosis of acute optic neuritis.

Acute Disease↗

PubMed1993

[Experimental laser sclerostomy ab externo with erbium:YAG laser].

A fistula from the anterior chamber of the eye into the subconjunctival space can be created by external laser application (laser sclerostomy). A pulsed (200 microseconds) Erbium-YAG laser was used because of the high scleral absorption. The laser energy was applied via a special fiber, which was inserted into a special application cannula to guide it into the subconjunctival space. A total of 24 rabbit eyes were treated and examined histologically after various postoperative periods. In all cases a functioning fistula and a marked reduction of the IOP (mean value 13 mmHg to 2 mmHg) were detected. On average, 60 mJ was required. The zone of thermal damage was limited to 40 microns. Cornea and lens showed no evidence of damage after 1 day or after 4 weeks. In the rabbit model, the fistulas were closed within 2 weeks, and long-term persistence of the fistula must therefore be verified in a clinical study. The method presented is minimally invasive, requires only a short operation time, causes minimal trauma to the conjunctiva, and may become an alternative to traditional fistulization operations.

Animals↗