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Biomedical subjects

M J Koch

Publications and source records attributed to M J Koch.

At least 19 recordsLinked to original sources
PubMed2000

Extrapulmonary tuberculosis in patients with end stage renal disease--two case reports and a brief review.

Chronic renal failure is a risk factor for tuberculosis. In the past five years we have identified two cases of tuberculosis in our dialysis population. The first patient, showed chronic failure to thrive on hemodialysis. An enlarged cervical lymph node was biopsied and, although no acid fast bacilli (AFB) were seen, a culture grew Mycobacterium tuberculosum (TB). Her chest X-ray did not show evidence of past tuberculosis. The second patient was a long time smoker who presented with an enlarged cervical node, which was biopsied. AFB were not seen on her biopsy, but her culture grew TB. Extrapulmonary TB is common in patients with ESRD, and lymph node involvement is the most common extrapulmonary presentation. Screening with the purified protein derivative (PPD) is not helpful in ESRD patients, since defects in cell mediated immunity are common. A high index of suspicion for TB is warranted in patients with ESRD.

Aged↗
PubMed2000

The clinical performance of laboratory-fabricated crowns placed on first permanent molars with developmental defects.

BACKGROUND: Young permanent molars with developmental enamel defects commonly are treated with stainless steel crowns. However, allergic reactions to nickel and chromium have been reported by some patients. The literature contains no evaluations of alternative treatments. METHODS: In a retrospective study, the authors evaluated the clinical performance of cast gold crowns and tooth-colored composite or ceramic crowns placed on first permanent molars with developmental defects in children 6 to 8 years of age. A total of 41 molars were prepared. After crown preparation, an impression was made, and crowns of cast gold, Artglass (J.F. Jelenko & Co.) composite or Empress (Ivoclar) leucite-containing ceramic were fabricated and clinically evaluated every six months for a period ranging from two to five years postoperatively (mean three years). RESULTS: After two to five years, all crowns were fully retained. The marginal adaptation of 39 of the 41 crowns was rated excellent, and the marginal adaptation of the remaining two crowns (both gold) received acceptable ratings. In two cast gold crowns, the margins were subgingival at cementation; the remaining 39 crowns had supragingival margins at the time of luting. By the end of the second year, all margins were supragingival. All teeth were vital and asymptomatic at all evaluation points. No secondary caries was recorded. Neither gingival inflammation nor loss of vertical dimension was recorded in any case. All crowns were well-accepted by the patients and their parents. CONCLUSIONS: Laboratory-fabricated crowns can be used for the treatment of young permanent molars with developmental defects. CLINICAL IMPLICATIONS: Cast gold, composite or ceramic crowns can be used successfully to treat developmental defects of first permanent molars in children.

Child↗
PubMed1999

Enamel hypoplasia of primary teeth in chronic renal failure.

Chronic renal failure (CRF) in the first years of life is associated with developmental defects of enamel in the permanent dentition. We investigated if CRF also affects the primary (deciduous) dentition. Thirty-one children with CRF on conservative treatment (n = 12) or on renal replacement therapy (n = 19) underwent dental inspection. In addition, 18 CRF children provided an exfoliated deciduous tooth for microscopic examination. Enamel defects were detected in a total of 12 children (31%), either clinically or microscopically. Of the 7 children affected clinically, 6 (19% of all examined) presented localized hypoplasia of the primary canines, which was found only in 3% of healthy control children: 1 patient had generalized pitted enamel hypoplasia. By microscopy, 5 of 10 primary canines examined showed enamel hypoplasia localized exclusively in enamel formed after birth. The "birth line," a visible structure within the primary enamel, was always present, which excludes a prenatal onset of the defects. Of the 12 patients with an enamel defect, 9 had a documented onset of CRF within the first 7 weeks of life. We conclude that renal disease leading to CRF may affect enamel formation of primary teeth in early postnatal life, resulting in lesions different from those observed in the secondary dentition.

Adolescent↗
PubMed1999

Formaldehyde release from root-canal sealers: influence of method.

AIM: To examine formaldehyde release from three different root-canal sealers: one phenol resin, one epoxy resin and one paraformaldehyde containing zinc oxide eugenol cement. METHODOLOGY: Formaldehyde was measured from freshly mixed material and from specimens allowed to set for 2 days or 2 weeks. Different mixing ratios and sample sizes were tested. Analysis was performed by reacting formaldehyde with acetylacetone and ammonia to form diacetyldihydrolutidine, which was revealed by spectrophotometry. RESULTS: Analysis revealed that mixing ratio, time after mixing and surface:weight ratios of specimens had different influences on the formaldehyde release from different materials. CONCLUSIONS: From the results of this study it is difficult to define a standardized in-vitro test that can be applied universally for the definitive determination of formaldehyde release from endodontic sealers. Prediction of in-vivo formaldehyde release from endodontic sealers is difficult.

Epoxy Resins↗
PubMed1999

Refractive cataract surgery.

Today, cataract surgeons can control postoperative refraction after cataract removal with improved intraocular-lens calculation formulas and minimal invasive surgery. However, a physiologically healthy status of the human lens (transparency, accommodation) cannot yet be regained completely postoperatively. Refractional outcome should be planned by the surgeon according to the patient's requirements. The preoperative planning also should include consideration of the intraocular-lens material needed.

Accommodation, Ocular↗
PubMed1998

[Correction of myopic astigmatism with the VISX 20/20 excimer laser. An overview of treatment outcome].

UNLABELLED: The advent of the excimer laser has brought about the potential for improved vision in many individuals with myopia and astigmatism. However, photoastigmatic refractive keratectomy (PARK) remains a matter of controversy. The purpose of our study was to determine the predictability of VISX 20/20 excimer laser photorefractive keratectomy in the treatment of myopic astigmatism. PATIENTS AND METHODS: Our study comprised 31 eyes of 22 patients with myopic astigmatism. All patients underwent treatment with a VISX 20/20 excimer laser and were followed up for 6 months. Complete 12-month follow-up data were available from 18 eyes. Park was performed in eyes with myopia between -1.5 and -10.0 D and with astigmatism between -0.5 and -5.5 D. Thus, the corresponding spherical equivalent ranged from -1.75 to -10.5 D. RESULTS: Six months postoperatively, 21/31 (62%) eyes were within +/- 1.0 D of the target refraction and 13/31 (42%) within +/- 0.5 D of the target refraction. In 13 of 15 eyes (87%) with myopia less than -6.0 D, an uncorrected visual acuity of at least 0.8 was noted. In eyes with myopia greater than -6.0 D, 9/16 (56%) showed an uncorrected visual acuity of at least 0.5. Six months after PARK, an increase of one line on the Snellen Visual Acuity Chart was observed in 8/31 (26%) and an increase of two lines was noted in eyes 3/31 (10%). One of 31 eyes (3%) showed an increase of three lines. A decrease in visual acuity of 1 line on the Snellen Visual Acuity Chart was found in 4/31 (13%), and in 3/31 eyes (10%) a decrease of 2-4 lines was noted. Overall, we observed a statistically significant reduction of astigmatism from 1.93 +/- 1.43 D to 0.93 +/- 0.63 D. Reduction of corneal astigmatism less than -1.25 D was not statistically significant. In eyes with astigmatism ranging from -1.25 to -2.5 D or greater than -2.75 D, a significant reduction of the mean astigmatism was noted. The postoperative regression of astigmatic correction was low. However, an axis shift of more than 15 degrees was found in 42%/35% of eyes by subjective refraction (miosis/cycloplegia) and in 33% in corneal topography. No central islands were noted. CONCLUSION: Photoastigmatic refractive keratectomy (PARK) constitutes a potential means of correcting myopic astigmatism. In eyes with astigmatism greater than -1.0 D a significant reduction of 60% of the mean astigmatism was noted. However, the considerable proportion of eyes with a postoperative axis shift greater than 15 degrees and a decrease in visual acuity of two or more lines indicates that further research is needed on excimer laser surgery to improve the reliability and safety.

Adult↗
PubMed1998

Refractive aspects of cataract surgery.

The refractive aspects of cataract or lens surgery has formed a new field of operations. To reduce astigmatism and high myopia, surgeons are looking into alternatives and using various incision techniques as well as phakic intraocular lenses or clear lens extraction to achieve emmetropia. High hyperopia with short axial length and high required intraocular lens power are corrected by piggyback intraocular lens implantation. The use of multifocal intraocular lenses compensates for the loss of accommodation after lens extraction.

Astigmatism↗
PubMed1997

Clinical evaluation of Helioseal F fissure sealant.

Unfilled resins are commonly in use as sealant material. In addition, there are filled sealants available. Helioseal F is a newly developed filled material with fluoride release. In this clinical trial, Helioseal F has been evaluated in one lower molar versus Delton opaque as an unfilled control in lower molars. After 12 months there were no significant differences in retention, porosities, and the number of clinically unacceptable margins between the materials. The complete retention was 30 out of 31 examined teeth for Delton and 28 out of 31 for Helioseal F. After 1 year of clinical testing, these results indicate that a sealant containing fluoride-releasing particles did not show a significant difference in retention rate compared to an unfilled conventional sealant. However, long-term results concerning marginal adaptation should be evaluated.

Adolescent↗
PubMed1997

Caries prevalence and treatment needs of 7- to 10-year-old schoolchildren in southwestern Germany.

The caries status of 1784 children aged 7 to 10 years was examined in a cross-sectional, epidemiological study in the Rhine-Neckar-District. Results showed that 30.5% of the children had caries-free primary and 65.2% had caries-free permanent teeth. The d(m)ft index was 2.68, and the D(M)FT averaged 0.76. As in previous studies, a high risk caries group was found, with 10% of all children showing more than 50% of all carious and filled teeth in the permanent dentition. Overall, 45.6% of the children's primary teeth and 16.3% of their permanent teeth needed treatment. As indicated by higher dt:ft (DT:FT) ratios in younger age groups, dentists preferred treating older children. Apart from a higher caries prevalence in primary teeth in males, no significant sex differences were found. Children of rural origin had a higher caries experience. The results confirm previous data showing considerable improvements with a declining caries experience in the young population. But the caries status of German pre-teenage children is still moderately high according to WHO criteria. For further improvements, considerable efforts have to be made with special emphasis on prevention in high risk caries groups.

Age Factors↗
PubMed1993

[Retinal hemodynamics in patients with arterial hypertension].

Arterial hypertension is a risk factor for the development of retinal, cerebral and renal microangiopathy. Therefore, a prospective study was started to investigate the progression of retinal microangiopathy in hypertensive patients. Initially, 254 patients were examined in a cross-sectional study. Following an ophthalmological examination, retinal hemodynamics were quantified by means of video-fluorescence angiography. Moreover, blood fluidity (hematocrit, plasma viscosity and erythrocyte aggregation) was analyzed. The severity of the retinal changes was defined according to the Neubauer classification. One hundred (40%) patients showed retinal changes corresponding to stage I; 133 (52%) were classified as stage II. Hypertensive retinopathy (stage III and IV) was encountered in 20 (8%) patients. Arm-retina time was significant prolonged among the hypertensive patients compared with a control group. Arteriovenous passage time showed no significant differences between hypertensive patients and reference values. Plasma viscosity was significantly increased in hypertensive patients and showed a significant increase with progression of the retinal changes. Hematocrit and erythrocyte aggregation were normal among the patients studied. The present findings show an alteration in blood fluidity among hypertensive patients, whereas retinal microcirculation showed no significant disturbances. Follow-up studies are planned to assess the development of retinal microcirculatory changes among hypertensive patients.

Adult↗
PubMed1992

[An outbreak of keratoconjunctivitis in a dairy farm].

An outbreak of infectious kerato-conjunctivitis is described in a dairy herd during the (winter)stable period. Moraxella was isolated from lacrimation fluid from three animals. The development of the infection was possibly precipitated by a vaccination with modified live IBR virus, adenovirus type 3 and parainfluenza virus type 3. Presumably, climatological-stable conditions play an important role in the clinical manifestation of the infection.

Animals↗
PubMed1992

Work patterns of male and female pharmacists. A longitudinal analysis 1959-1989.

A demand for better data about pharmacists as working health professionals led the authors to study the work patterns of 1,146 pharmacists over a 30-year period from 1959 to 1989. Work history data were used to determine gender-specific participation rates as a function of age, years in the work force, and date. Percent full-time (as opposed to part-time) work as a gender-specific function of age was also determined. Participation rates for males and females, widely disparate in the 1960s, have converged and are not significantly different. Graduates of the 1980s, both male and female, are remaining with pharmacy as an occupation at a significantly higher rate than earlier graduates. Percent full-time rates for women pharmacists are significantly lower than those for male pharmacists, although women have registered significant increases in percent full-time work in each decade from the 1960s to the 1980s. An unexpected finding was the overall reduced participation by graduates of the years 1970 to 1979. The findings of the study are helpful in explaining recent controversies about the adequacy of the supply of pharmacists. The form of the data bases constructed for this study could be used as a model for the study of other health professionals.

Adult↗
PubMed1990

Crystalloid lysozyme inclusions in Paneth cells of vitamin A-deficient rats.

The effect of vitamin A-deficiency on jejunal Paneth cells in rats was investigated. Crystalloid particles were observed in secretion granules of Paneth cells from 6 out of 8 rats with vitamin A-deficiency. The particles were similar to those found in Paneth cells under other experimental conditions. Using an immuno-electron-microscopic technique we demonstrated a clear lysozyme immunoreactivity of these particles. In 2 vitamin A-deficient rats tubular structures have been detected in addition to the crystalloid particles. Crystalloid particles or tubular structures were not detectable in a control group of 8 vitamin A-supplemented rats. The morphological alterations of Paneth cells may be correlated to an impaired local immunity of the intestine during vitamin A-deficiency.

Animals↗
PubMed1988

Intestinal transport and metabolism of oxidized ascorbic acid (dehydroascorbic acid).

The transport and metabolic properties of dehydroascorbic acid have been evaluated in the small intestine of one ascorbic acid-dependent animal species (guinea pig) and one ascorbic acid-synthesizing animal species (rat). Loops of guinea pig jejunum in vitro brought about net transepithelial absorption of L-[14C]dehydroascorbic acid with most of the absorbed substrate appearing in the reduced form (ascorbic acid). Saturation of brush-border transport occurs at a lower concentration than saturation of the enzymatic reduction. Rat intestine did not bring about net transepithelial transport. The intestines of both guinea pigs and rats took up substantial dehydroascorbic acid from the serosal bathing solution, with the majority appearing in the mucosa as ascorbic acid. It is proposed that in guinea pig intestinal mucosa, dehydroascorbic acid reductase has a nutritional role in extracting the vitamin from chyme and reducing it for subsequent use in the body. The intestines of both guinea pig and rat appear to take up dehydroascorbic acid across the basolateral surface and reduce it, thus maintaining a substantial endogenous level of ascorbic acid in the mucosa. The transport and metabolic properties described might play an important role as a protective antioxidant mechanism in intestinal mucosa.

Animals↗
PubMed1984

Liquid chromatographic behavior of ascorbate on amine columns.

Quantitation of ascorbate at concentrations normally found in biological samples and foods has previously been shown to be possible by HPLC analysis. Prefilled amine columns from three manufacturers were presently used to evaluate their potential for separating low concentrations of [14C]ascorbic acid from its degradation products, [14C]dehydroascorbic acid and [14C]diketogulonic acid. A successful separation was achieved on some columns with as little as 200 cpm (30 pmol) of total ascorbate injected. On other columns, injection of 30-500 pmol of ascorbate resulted in as much as 80% of [14C]ascorbic acid eluting with an unpredictable retention time. In these instances the inclusion of nonlabeled ascorbic acid (0.5 mg/ml) to the sample resulted in most of the [14C]ascorbic acid activity eluting at the expected retention time of ascorbic acid. The inclusion of ascorbic acid in samples injected onto the column also resulted in a more discrete peak in the elution of dehydroascorbic acid, and more complete recovery of the total [14C]activity (ascorbic acid, dehydroascorbic acid, and diketogulonic acid) injected onto the column.

Amines↗