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Biomedical subjects

H Sachs

Publications and source records attributed to H Sachs.

At least 19 recordsLinked to original sources
PubMed2001

[Subretinal microphotodiode array as replacement for degenerated photoreceptors?].

A survey is given on the status of developments, concerning a subretinal electronic microphotodiode array that aims at replacing degenerated photoreceptors. Various prototypes have been developed, tested, and implanted in various experimental animals up to 18 months. The fact that electrical responses were recorded from the visual cortex of pigs after electrical stimulation by subretinal electrodes and the fact that responses are also recorded in-vitro in degenerated rat retinae, shows the feasibility of this approach. However, there are a number of open questions concerning the biocompatibility, the long-time stability, and the type of transmitted image to be solved before application in patients can be considered.

Animals↗
PubMed2000

Detection of THCCOOH in hair by MSD-NCI after HPLC clean-up.

Regular consumption of cannabis can easily be detected by examination of hair for tetrahydrocannabinol, cannabinol, and cannabidiol. Although several studies have demonstrated that after contamination with smoke or treatment with THC containing shampoos THC is not detectable, or only in small traces, the detection of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH) should be offered to prove the consumption and metabolisation of THC. Up to now this confirmation was only available using tandem MS techniques combined with negative chemical ionisation. A new method using a normal quadrupole GC/MS is described. The lack of expensive instruments has to be paid for by a costly and time consuming extraction and clean-up. After the sample has been digested by 2 M NaOH at 95 degrees C and the neutralised liquid has been extracted with a mixture of n-hexane and ethyl acetate the dried residue is reconstituted in acetonitrile-methanol-0.01 M sulfuric acid (49:21:30, v/v/v) and the cannabinoids separated by HPLC. Each fraction is collected over 1 min. Another extraction with n-hexane-ethyl acetate is followed by evaporation, derivatisation, and GC/MS determination. The calibration with THCCOOH spiked hair led to a LOD of 0.3 pg/mg and a LOQ of 1.1 pg/mg.

Chromatography, High Pressure Liquid↗
PubMed2000

Analytical strategy for detecting doping agents in hair.

Lists of banned classes of doping agents are released by the International Olympic Committee, adopted by other sports authorities and updated regularly, including the substance classes stimulants, narcotics, diuretics, anabolic agents, peptide hormones, beta-blockers etc. There are different classes of restriction: anabolic and masking agents (anabolic steroids, diuretics etc.) are always banned for athletes regardless of their topical activity (training or competition) several substances are permitted with certain restrictions (caffeine below a cut-off value, or inhalation of some beta 2 agonists) beta-blockers are prohibited in competitions of certain sports disciplines the majority of the substances (stimulants, narcotics etc.) is prohibited during competitions, so that they do not have to be analysed in out-of-competition samples. A differentiation between training and competition period is impossible by means of hair analysis due to the uncertainty of (especially short-term) kinetic considerations related to hair growth. Therefore, the analytical identification of doping relevant substances in hair is not always a sufficient criterion for a doping offence and the identification of stimulants, beta-blockers etc. in hair would be entirely irrelevant. The most interesting target substances are certainly the anabolic agents, because their desired action (enhanced muscle strength) lasts longer than the excretion, leading to sophisticated procedures to circumvent positive analytical results in competition control. Besides the analysis of out-of-competition control samples, the long term detection of steroids in hair could provide complementary information. An analytical approach to the identification of exogenous steroids in hair requires consideration of the presence of many other steroids in the hair matrix interfering the analysis at trace levels, and of a limited chemical stability. The analysis of endogenous steroids in hair appears to be even more complicated, because the possibility of many biotransformation reactions from (into) other precursors (metabolites) has to be taken into account. Precursor substances of anabolic steroids (especially esters as application forms) are very promising analytical targets of hair analysis, because they can only be detected after an exogenous intake. The quantitative evaluation of active parent compounds like testosterone (which is actively involved in physiological processes of hair growth) in hair is still controversial. Clinical applications under reproducible conditions can be useful, but the biovariability of these parameters will probably prevent the definition of acceptable cut-off levels as a criterion of abuse.

Adrenergic beta-Antagonists↗
PubMed1999

Testing for anabolic steroids in hair from two bodybuilders.

Two male bodybuilders were recently arrested by the French customs in Strasbourg (France) in possession of 2050 tablets and 251 ampoules of various anabolic steroids. It was claimed that the steroids were for personal use and not for trafficing as suggested by the police. Urine and hair specimens were collected from both suspects to clarify the claims. Nandrolone, stanozolol, testosterone and their corresponding metabolites were identified in the urine of both subjects. After decontamination, the hair was hydrolyzed by sodium hydroxide in presence of deuterated internal standards. After extraction with ethyl acetate and silylation, the drugs were identified by GC-MS in the electron impact mode. Hair from both males were positive for nandrolone (196 and 260 pg/mg), testosterone (46 and 71 pg/mg) and stanozolol (135 and 156 pg/mg), clearly indicating steroids abuse. Although not yet recognized by the International Olympic Committee, hair analysis may be a useful adjunct to conventional drug testing in urine from athletes.

Anabolic Agents↗
PubMed1998

Testing for drugs in hair. Critical review of chromatographic procedures since 1992.

Up to now, more than 50 pharmaceuticals or drugs of abuse have been reported to be detectable in hair after oral or parenteral administration. The present paper reviews the literature devoted to drug testing in hair that has been published since 1992. Procedures for the detection of opiates, cocaine, amphetamines and cannabis in hair are described in detail. In particular, the papers on benzodiazepines show an increasing number of procedures using negative chemical ionisation with GC-MS and diode array detection with HPLC in hair analysis. For the most important benzodiazepines, diazepam and flunitrazepam, reliable methods now exist. On the other hand, the problem of the detecting tetrahydrocannabinol metabolites using different techniques is not yet solved. Some progress is observed in the detection of low dose drugs, like fentanyl and its derivatives or LSD. For most of the analyses using chromatographic techniques, the main data on sample preparation and analytical determinations are listed. Some new findings, based on the experience of the authors, are also added.

Amphetamines↗
PubMed1997

Quality control by the Society of Hair Testing.

In contrast to urine and blood analyses the amount of hair samples lies in the order of 20-100 mg. Consequently at similar concentrations the absolute detection limit is about one order lower, increasing the relative deviation. The interlaboratory differences are correspondingly high. Concerning blood and urine, calibrators and controls are produced by adding certain amounts of the drug to the negative sample. Usually the single determinations are calibrated with spiked hair samples. These samples cannot be used as controls because in real hair the drug is bound to a solid phase surrounded by keratin, whereas in a spiked sample the drug is bound to the surface of the hair and can easily be washed away by any liquid phase. Recently some round robin surveys have been performed by several laboratories, some using drug soaked hair to detect contamination, the other using powdered hair of drug addicts to compare quantitative results. In this contribution the manufacturing of the hair pools and the results of the last international interlaboratory comparison will be described and future activities of the Society of Hair Testing are presented.

Germany↗
PubMed1996

Analysis of fentanyl and sufentanil in hair by GC/MS/MS.

Fentanyl and sufentanil are potent narcotic analgesics used only in hospitals as anaesthetic agents. The dependence potential of fentanyl is known. As they are given in doses at the microgram level and their elimination half-life is in the order of a few hours, detection in body fluids is possible only for a short time after administration. Radioimmunological methods are the only ones capable of detecting fentanyl in hair, as normal GC/MS methods for hair analysis are not sensitive enough to detect the drugs after doses in the order of micrograms. We therefore chose GC/MS/MS to analyse fentanyl and sufentanil in two cases where the drugs were given under controlled conditions over several days. The concentration was in the order of less than 100 pg/mg hair.

Anesthetics, Intravenous↗
PubMed1996

[Single dose intraoperative administration of 5-fluorouracil (5-FU) in trabeculectomy. Long-term results of a pilot study].

5-Fluorouracil (5-FU) improves the success of trabeculectomy. Since in vitro studies showed a prolonged effect of 36 days of growth inhibition with a single dose of 5-FU, 5-FU is applied intraoperatively. To evaluate the effect of intraoperatively applied 5-FU, we compared 13 (low-risk) patients with intraoperative application of 5-FU to a control group matched by age, diagnosis, sex and stage of glaucoma. Postoperatively on day 4 the IOP was significant lower (4.8 mmHg) in the 5-FU-group in comparison to the untreated group (P = 0.005; power 0.80). After 1 week the difference decreased to 2 mmHg and was not significant any more (P = 0.16). After 1 week a lower mean intraocular pressure of 2 mmHg was found with a P-value of 0.16. It may be that these results are not just due to an antiproliferative mechanism; a direct toxic effect of 5-FU should be considered. 5-FU side effects such as corneal complications and inflammatory reaction were not increased in the 5-FU group. However, one case of persistent hypotony was seen in the 5-FU group. This study found intraoperative use of 5-FU to be a safe procedure with a pronounced capacity to lower IOP in the direct postoperative phase. However, this effect may not be based on an antiproliferative effect alone, but might be of toxic origin.

Aged↗
PubMed1996

[Treatment of recurrent corneal erosion using phototherapeutic keratectomy with the excimer laser].

BACKGROUND: Recurrent corneal erosion is a common corneal disease and may be a difficult disorder to treat with a number of patients suffering persistent symptoms despite conventional therapy. PATIENTS AND METHODS: We present a series of 32 eyes who underwent Excimer-Laser phototherapeutic keratectomy (PTK) for recurrent corneal erosion. There were 11 eyes who were treated during an acute episode of recurrent erosion. All remaining patients were treated in a symptom-free interval. The affected area of epithelium was removed and a 25 pulse ablation was performed to Bowman's membrane. RESULTS: In 30 eyes there was a marked improvement in symptoms postoperatively with no recurrences. However, 2 eyes experienced a recurrent episode 6 days and 2 weeks after PTK, respectively. Postoperative refraction and corneal topography was unaltered in all cases. CONCLUSIONS: Excimer-Laser PTK appears to be a safe and promising procedure for recurrent corneal erosion in cases refractory to medical treatment.

Adult↗
PubMed1996

Excimer laser phototherapeutic keratectomy for recurrent erosions: a clinical study.

BACKGROUND AND OBJECTIVE: Recurrent corneal erosion is a common corneal disease. It may be difficult to treat, with a number of patients suffering persistent symptoms despite having had conventional therapy. The aim of this study was to evaluate the usefulness of the excimer laser for the treatment of recurrent corneal erosions. PATIENTS AND METHODS: The authors studied 31 eyes of 24 patients who underwent excimer laser phototherapeutic keratectomy (PTK) for recurrent corneal erosion. Three eyes were treated during an acute episode of recurrent erosion. The remaining eyes were treated during a symptom-free interval. The affected area of epithelium was removed and a 25 pulse ablation was performed to Bowman's membrane. RESULTS: In 30 eyes there was a marked improvement in symptoms postoperatively, with no recurrences. However, 1 eye had one recurrent episode 2 weeks after PTK. Postoperatively, refraction and corneal topography were unaltered in all cases. CONCLUSIONS: Excimer laser PTK appears to be a safe and promising procedure for cases of recurrent corneal erosion refractory to medical treatment.

Adult↗
PubMed1995

Theoretical limits of the evaluation of drug concentrations in hair due to irregular hair growth.

When examining concentration relationships of doses it must be taken into account that hair growth is irregular. Hair growing from the shaved skin after a single dose of a certain drug cannot possibly contain the same concentration as hair after the same dose that has not been cut over a long period. Concentrations can even change during the hair growth in cases where the hair had been cut a couple of months before the hair sample was taken. The variations in the expected concentrations can exceed 20%. On the other hand, the evaluation of a hair tuft which has grown after the last drug consumption may be important in forensic cases where the hair which has grown earlier is not available. This may lead to misinterpretations at low concentrations. Expected concentrations are calculated assuming a telogen part of 10%.

Hair↗
PubMed1995

Sleep and psychological characteristics of children on a psychiatric inpatient unit.

OBJECTIVE: To assess the association of objective measures of sleep-wake patterns and psychological status and abuse history of children hospitalized in a psychiatric inpatient unit. METHOD: Thirty-nine inpatient children participated in the study. They were monitored for one to three consecutive nights with miniature wrist activity monitors for objective assessment of sleep-wake patterns. In addition, a thorough psychiatric and psychosocial assessment was completed with each child and the parents. RESULTS: Children's self-ratings of depression, hopelessness, and low self-esteem were significantly correlated with objective sleep measures indicating poorer sleep quality. No significant correlations between intelligence scores and sleep measures were found. Nonabused and sexually abused children had better sleep quality than physically abused children. CONCLUSIONS: Sleep quality during hospitalization is strongly associated with self experiences of depression, hopelessness, and low self-esteem in children with severe behavior disorders.

Adolescent↗
PubMed1995

[ProTon--a new portable tonometer. Initial experimental and clinical results].

To determine the accuracy of a new portable tonometer using the Mackay Marg principle (ProTon, Tomey) we measured three cadaver eyes in vitro and 196 eyes of 98 patients in vivo. The 325 manometric determined IOP values were compared to ProTon measurements in three enucleated, canulated human eyes. The correlation was r = 0.99. In a clinical study 196 eyes were measured with both the Goldmann and the ProTon tonometer. The results showed good correspondence with a correlation of r = 0.95. The statistical significance (paired t-test) was P < 0.001.

Equipment Design↗
PubMed1994

Somatic, cognitive and emotional characteristics of abused children in a psychiatric hospital.

A systematic review of medical records of one hundred consecutive admissions to a children's psychiatric inpatient unit was conducted to assess specific somatic, cognitive and emotional characteristics that distinguish sexually abused children from other hospitalized children. Sexually abused children were characterized by: a lower performance IQ, higher incidence of parasomnia prior to admission, longer length of hospital stay, and comparatively small physical stature.

Adolescent↗
PubMed1993

Determination of dihydrocodeine in hair of opiate addicts by GC/MS.

After the examination of more than 300 hair samples of suspected heroin abusers, a large number of which proved positive, we can say that high concentrations of dihydrocodeine can be determined either in addition to, or in the place of, morphine and also frequently in combination with codeine. The opiates were extracted after dissolving the hair samples in NaOH and hydrolysis with HCl. The quantitative determination of dihydrocodeine was achieved by derivatisation with HFBA using GC/MS at m/u = 497. Dihydrocodeine is used in antitussive drugs. After the examination of individual hair samples, it was obvious that some heroin consumers had switched to dihydrocodeine. This may lead to the conclusion that dihydrocodeine itself is used either as an intoxicating drug or to reduce withdrawal symptoms. The increasing number of positive samples should be noted by the legal authorities.

Codeine↗
PubMed1993

Hair analysis as evidence in forensic cases.

Because hair analysis can be used for the determination of drug use months after drug consumption, hair analysis data can often act as important and even decisive evidence in the courtroom. More recently developed GC/MS methods offer excellent sensitivity and can make the distinction between chronic heroin and codeine use, which was not possible earlier with radioimmunoassay techniques. From more than a thousand hair analyses, the morphine/codeine ratios necessary to determine heroin use were set at 5:1 for low morphine concentrations (< 1 ng/mg hair) and 2:1 for concentrations above 1 ng/mg hair. The distinction can be further focused with the additional analysis of the metabolite monoacetylmorphine (MAM). As can be seen from several case examples, hair analysis cannot pinpoint an exact date of opiate use, but it can be used to validate or invalidate a subject's statement concerning his/her drug consumption. Interpretations should always be made cautiously. Ranges, means and medians are also listed for amphetamine, cocaine and cannabis and work is under way to draw similar safety guidelines for these drugs.

Codeine↗