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Biomedical subjects

J M Koch

Publications and source records attributed to J M Koch.

At least 19 recordsLinked to original sources
PubMed2006

Effect of melengestrol acetate as an alternative to induce molting in hens on the expression of yolk proteins and turnover of oviductal epithelium.

Inducing hens to molt increases egg quality, egg production and extends the productive life of hens. It has been previously demonstrated that melengestrol acetate (MGA), an orally active progestin, decreased gonadotropic support for the ovary, which decreased the steroidogenic support for the oviduct and resulted in the cessation of lay. Estradiol produced by the theca cells of small follicles stimulates the production of the yolk proteins vitellogenin II and apolipoprotein II by the liver and supports the oviductal epithelial cells. The objective of the present experiment was to determine gene expression for yolk proteins and oviductal epithelial cell turn-over in response to a MGA-induced molt. Hy-Line W-36 laying hens were fed either 0 or 8mg MGA per day for 28 days in a balanced diet and then returned to a standard layer ration until day 36. Four birds per treatment on days 1, 8, 16, 28 and 36 were euthanized and the liver was removed and snap frozen in liquid nitrogen until RNA was extracted. Expression of vitellogenin II and apolipoprotein II genes was determined using real-time RT-PCR. A portion of the magnum was removed to determine proliferation and programmed cell death for secretory and ciliated luminal epithelium. Vitellogenin II and apolipoprotein II gene expression was reduced in hens fed 8mg MGA compared to those fed 0mg MGA. There was no effect of day on gene expression of either yolk protein. Cell proliferation was increased in the ciliated epithelial cells of the oviduct in hens receiving 8mg MGA compared to those receiving 0mg. However, programmed cell death of the ciliated epithelial cells was not different between controls and MGA treatment. Programmed cell death and proliferation increased in the secretory epithelial cells in hens receiving 8mg MGA compared to controls. Therefore, utilizing MGA as an alternative method to induce molt results in some, but not all, of the physiological changes previously described for hens molted by feed withdrawal. These findings lead us to suggest that some of the observed physiological changes resulting from feed withdrawal are required to increase egg quality and egg production following molt and other changes are not necessary, but are just a result of nutrient deprivation.

Animal Feed↗
PubMed2006

Transscleral diode laser cyclophotocoagulation as primary surgical treatment for secondary glaucoma in juvenile idiopathic arthritis: high failure rate after short term follow up.

AIM: To evaluate the success rates of transscleral diode cyclophotocoagulation (TD-CPC) for secondary glaucoma in patients with juvenile idiopathic arthritis (JIA) as primary surgical treatment. METHODS: Retrospective chart review of 12 paediatric patients with JIA associated uveitis and secondary open angle glaucoma. RESULTS: 21 eyes of the 12 patients had chronic anterior uveitis, 21 eyes had secondary open angle glaucoma, and 19 eyes were treated 41 times with TD-CPC. Patients underwent a mean of 2.15 treatment sessions per eye. Pretreatment intraocular pressure (IOP) was 30.2 (5.5) mm Hg before the first treatment, 30.5 (5.7) mm Hg before the second treatment, and 28.7 (6.3) mm Hg before the third treatment. Reduction of IOP 6 weeks after treatment was highest after the second and third treatments with 9.4 (8.8) and 8.7 (5.8) mm Hg, respectively and 5.2 (10.7) mm Hg after the first treatment. Qualified success (IOP </=21 mm Hg with glaucoma medication) was achieved at the end of follow up in six of 19 eyes (32%, follow up time 10.1 (9.3) months). CONCLUSION: TD-CPC as a primary surgical treatment in JIA patients, is often unsatisfactory in eyes with uveitic glaucoma.

Antihypertensive Agents↗
PubMed2005

Melengestrol acetate in experimental diets as an effective alternative to induce a decline in egg production and reversible regression of the reproductive tract in laying hens. I. Determining an effective concentration of melengestrol acetate.

Induced molting increases egg quality and egg production and extends the productive life of hens. Molting is accomplished by feed withdrawal, which has been criticized for not addressing hen well-being, and current alternatives have resulted in poor postmolt performance and inadequate well-being. Molting leads to regression of follicles on the ovary and causes loss of steroidogenic support for the oviduct, leading to cessation of lay. Melengestrol acetate (MGA), an orally active progestin, may decrease support for the ovary, resulting in loss of support for the oviduct, while hens are fed a balanced diet. In this experiment, a dose response study, Hy-Line W-36 hens were fed 0, 0.1, 1, 4, or 8 mg of MGA per hen/d in a balanced diet for 28 d and then returned to a normal diet. Four birds on d 0 and 4 birds per treatment on d 1, 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, and 44 were euthanized. The weight of the ovary with follicles, magnum, shell gland, and oviduct were determined. A decrease in egg production was observed in those groups receiving 4 and 8 mg of MGA, until removal of MGA from the diet. After d 28, egg production increased to the production level of hens fed 0, 0.1, or 1 mg of MGA. The weight of the ovary with follicles, oviduct, magnum, and shell gland were unchanged throughout in groups fed 0, 0.1, or 1 mg of MGA. However, groups fed 4 or 8 mg of MGA exhibited a decrease (P < 0.05) in the weight of the ovary with follicles, oviduct, magnum, and shell gland until d 28. Recrudescence of the large yellow follicles as well as rejuvenation of the oviduct and its components, the magnum and shell gland, in the 4 and 8 mg MGA groups occurred by d 44. Melengestrol acetate, fed to hens on a balanced layer diet, caused reversible regression of follicles and, therefore, removal and return of support for the oviduct.

Aging↗
PubMed2005

Melengestrol acetate as an effective alternative to induce a decline in egg production and reversible regression of the reproductive tract in laying hens. II. Effects on postmolt egg quality.

Induced molting increases egg quality and egg production and extends the productive life of hens. Molting is accomplished by feed withdrawal, which has received criticism, and alternatives described thus far result in poor postmolt performance. Melengestrol acetate at a dosage of 4 or 8 mg/d, in a balanced diet, leads to reversible regression of the reproductive tract. However, this alternative must also increase egg quality after rest to be considered an adequate method by the industry. Hy-Line W-36 (n = 497) laying hens were assigned randomly to a diet containing 0 mg of melengestrol acetate (MGA; control) throughout the experiment or 4 or 8 mg of MGA/d for 2, 4, or 6 wk. Upon reaching 50 and 70% lay, after MGA removal, eggs were collected for measurements of egg quality, including Haugh units (i.e., internal egg quality), shell thickness, and breaking strength (i.e., external egg quality). Haugh units were greater (P < 0.05) for eggs laid by hens molted with a diet containing 8 mg of MGA for all durations compared with controls. Shell thickness was greater (P < 0.05) when hens were treated with 4 mg of MGA for 6 wk and 8 mg of MGA for 4 and 6 wk compared with control. Egg breaking strength was greater (P < 0.05) than controls for all hens fed MGA, regardless of dosage or duration of feeding. A subset of hens was fed 8 mg of MGA per hen/d for 2 wk, and eggs were collected for 3 wk. Seven days after MGA was removed from the diet, the amount of MGA in the yolk was below the level of detection of the assay, and the concentration found in the eggs at all time points was 3 orders of magnitude below the Food and Drug Administration's tolerance for MGA in edible tissue. When used as an alterative method to induce a rest, MGA leads to an increase in the internal and external egg quality of hens compared with nonmolted hens.

Aging↗
PubMed2003

Management of acute ulcerative and necrotising herpes simplex and zoster keratitis with amniotic membrane transplantation.

AIM: To report promoted healing of acute ulcerative and necrotising herpetic keratitis after amniotic membrane transplantation (AMT). METHODS: Retrospective, non-comparative case series of seven patients with acute ulcerative and necrotising herpetic stromal keratitis. Single or multilayer AMT with epithelial side facing up was performed. The main outcome measures were wound healing of the corneal ulcers and decrease of stromal inflammation. RESULTS: The mean follow up was 10.7 (SEM 1.4) months (range 5-15 months). AMT was performed once in five cases, and twice in further two. Improvement of stromal inflammation was noted within 16.4 (2.5) days (range 7-28 days). Epithelial defects healed within a mean of 17 (2.7) days (range 7-28 days). Vision improved in all but two patients. No serious side effects occurred during the follow up. CONCLUSIONS: Although performed in an uncontrolled and non-randomised series of patients, these findings indicate that the AMT shows promise in selected cases for the restoration of ocular surface integrity, reduction of stromal inflammation, and improvement of vision in acute ulcerative and necrotising herpetic keratitis.

Acute Disease↗
PubMed1995

Prevalence of age-related macular degeneration.

Early and late age-related macular degeneration (AMD) have a high prevalence in elderly patients but may be differentiated by medical or environmental factors, eg, hypertension, geographic area, or antioxidant agents. Because nuclear sclerotic cataract is associated with AMD both aging changes may share a common pathogenesis. The genetic predisposition for AMD is indicated by the identical appearance in monozygotic twins, but genetics may be also important for the explanation of the low incidence of late AMD in black individuals. Specific ocular characteristics like light or depigmented iris color, prolonged dark adaptation, and decreased foveal flicker sensitivity are also risk factors for AMD. Early AMD characteristics with high risk for late AMD are confluent drusen, focal hyperpigmentation, or atrophy and slow choroidal fluorescein filling. Therefore specific genetic, environmental, medical, and ocular characteristics determine the individual appearance and progress of AMD. The knowledge of these factors may result in new prophylactic and specific treatments for AMD.

Aged↗
PubMed1995

[Diagnosis and and differentiation of dry eye disorders].

Artificial tears often fail in dry eye patients. Our goal was to establish a diagnostic approach that involves alternatives that are more effective for the treatment. We examined 110 patients with dry eyes not stabilized by artificial tears: medical history, visual acuity, slit lamp examination, rose bengal stains and fluorescein stains, Schirmer test, break-up time (BUT), dye tests, impression cytology, and lid transillumination. This allowed disturbances of the three layers of the tear film (lipid, aqueous, mucin) to be differentiated. Cellular damage of the ocular surface was evaluated and scored by slit lamp examination, rose bengal staining, and impression cytology. Only 8% of the patients with "sicca syndrome" had exclusive aqueous deficiencies amenable to artificial tears. In contrast, lipid deficiencies (chronic blepharitis) were determined most frequently (78%). Twenty-six percent had disturbances in two or more layers of the tear film. The diagnostic strategy of differentiating disturbances of the layers of the tear film offers a more specific approach to the treatment of dry eyes.

Adult↗
PubMed1994

[Therapy of dry eye disorders].

BACKGROUND: The treatment of dry eyes with artificial tears often fails. We differentiated the disturbances of the three layers of the tear film in 90 such patients. This showed that only 11.1% had aqueous deficiency, while 42.3% had combined disturbances of different layers of the tear film, and 76.7% had lipid deficiencies. PATIENTS AND METHODS: We now studied the efficacy of a therapeutic approach, which intended to stabilize each individual deficiency of the three layers of the tear film (follow-up > or = 6 months). The medical history, visual acuity, slit lamp examination, rose bengal stains and fluorescein stains, Schirmer test, break-up time (BUT), dye tests, impression cytology, and lid transillumination were analyzed. RESULTS: Therapy was beneficial in all patients (n = 90) with regard to the symptoms and the objective parameters. Artificial tears applied strictly were without preservatives. Patients with toxic conjunctivitis induced by high dosages of eye drops were often stabilized through withdrawing the medication. The frequency of applying artificial tears was significantly tapered by punctum plugs and -coagulation. Tarsorrhapies were helpful in the most severe cases. Topical retinoids significantly reduced the symptoms and increased the goblet cell density. Treating chronic blepharitis was very sufficient, when initiated by topical steroids and Tetracycline, and systemical Doxycycline. CONCLUSIONS: Differentiating the disturbances of the three tear film layers in "sicca syndrome", and stabilizing each component is more effective than artificial tears alone.

Combined Modality Therapy↗
PubMed1993

Angioscopic evaluation of periprocedural and postprocedural abrupt closure after percutaneous coronary angioplasty.

Abrupt closure remains a significant complication of PTCA. On the basis of the presumption of underlying cause (thrombus, dissection, spasm), various empiric medical and mechanical interventions have been used to prevent and/or treat this event. Despite these measures, however, abrupt closure remains a highly unpredictable occurrence with a substantial incidence of myocardial infarction and angioplasty-related morbidity and mortality. Direct visualization of the site of abrupt closure may allow determination of responsible mechanisms and appropriate treatment strategies. Intracoronary visualization using a new angioscope was carried out in two cases of abrupt closure after percutaneous coronary angioplasty. The angioscope features a movable fiberoptic bundle that provides continuous and uninterrupted imaging of the coronary artery segment incorporating the site of abrupt closure. In one patient with intraprocedural closure angioscopy revealed obstruction of the lumen with extruded plaque material. In a second patient with postprocedural closure, however, imaging at the site of coronary artery occlusion revealed a mass consistent with a large platelet thrombus. Intracoronary evaluation with angioscopy may yield important characteristics that identify lesions at risk for abrupt closure. Further elucidation of the mechanisms underlying abrupt closure may allow more appropriate selection of therapeutic interventions.

Aged↗
PubMed1993

[Ocular complications of long-term survival of bone marrow transplantation. A prospective study with 21 patients].

BACKGROUND: Survival time after bone marrow transplantation is getting increasingly longer and secondary ocular complications need to be identified and deserve more attention as so far. PATIENTS AND METHODS: We evaluated the ocular complications of 21 not selected, long-term survivors after bone marrow transplantation in a prospective study. The ophthalmological examination consisted of visual acuity, slit lamp examination, tonometry and ophthalmoscopy. It included also determination of tears break-up-time, Jones-test, rose bengal staining and impression cytology of the conjunctiva. RESULTS: The major ocular complication was the development of a keratoconjunctivitis sicca syndrome in 14 of the 21 patients. This complication is probably due to the total-body irradiation in the preparative before and to the development of a chronic Graft-versus-Host-Disease after transplantation. 13 of the 21 patients developed a cataract. This might be a result of the total-body irradiation and a prolonged high steroid intake. CONCLUSION: The frequency and severity of ocular complications suggest that detailed ocular examinations should be performed routinely in patients after bone marrow transplantation.

Anemia, Aplastic↗
PubMed1992

[Acanthamoeba keratitis caused by extended wear contact lenses].

A 68 year old female with aphakic soft lenses on an extended wear basis developed an Acanthamoeba-keratitis. The diagnosis could be confirmed by a positive culture of a corneal smear, the contact lens and the care solution. Immediate antibiotic therapy including aminoglycosides and cephalosporines topically showed response with clearing of the stromale infiltrates and, as a residuum, the development of small stromal scars at the former site of inflammation. An Acanthamoeba-keratitis should be considered in the differential diagnosis of all cases of keratitis in contact lens wearers that are unresponsive to topical medical therapy and without bacterial growth on routine cultures.

Acanthamoeba Keratitis↗
PubMed1992

[The pterygium, Autologous conjunctiva-limbus transplantation as treatment].

Based on a new concept of the limbus as a junctional zone for separating the vascularized conjunctiva from the avascular cornea, this study presents conjunctival/limbal autograft transplantation for 22 cases of pterygium. The pterygia were primary in 17 eyes, cicatricial in 1 and recurrent in 4. In all cases a free transplant of the superotemperal limbus with an adjacent piece of thin conjunctiva was placed in the excision area. Postoperative follow-up ranged from 1 1/2 to 17 months, with a mean of 8.7 months. Only two pterygia recurred. In all other cases ideal anatomic reconstruction was achieved without any side effects. The authors believe that conjunctival/limbal transplantation is an encouraging technique for treating a pterygium surgically.

Conjunctiva↗
PubMed1991

Corneal edema after overnight lid closure of rabbits wearing silicone rubber contact lenses.

Elastofilcon A silcone rubber contact lenses induce less corneal swelling than no lens wear during sleep, and increasing the central thickness and volume of the lens does not influence its overnight performance. We sought to elucidate whether a silicone rubber lens can promote the distribution of atmospheric O2 on the cornea through a small interpalpebral opening under closed-eye conditions. Three groups of rabbit eyes comprised 12 eyes wearing Silflex (Dk 79.8 barrer) lenses, 12 with elastofilcon A (Dk 340 barrer) lenses, and 12 without lenses. All eyes were surgically closed overnight; six eyes in each group had a complete lid closure and six eyes had a partial tarsorrhaphy that left a small, central gap approximately 3 mm in length. When the lids were opened the next morning, the partially closed elastofilcon A eyes showed less corneal swelling (6.2 +/- 1.4%) than the partially closed no-lens eyes did (9.6 +/- 1.3%) (p less than 0.01), whereas the partially closed Silflex eyes were significantly more swollen (12.8 +/- 2.1%) (p = 0.01) than the other two partially closed groups were. The completely closed eyes showed no significant difference in corneal swelling among the groups. These results indicate that small lid gaps during sleep may lead to less corneal swelling when elastofilcon A lenses are used than with no lenses.

Animals↗
PubMed1990

Experimental Pseudomonas aeruginosa keratitis from extended wear of soft contact lenses.

We used a rabbit model to investigate the pathogenesis of soft contact lens-induced bacterial keratitis. Rabbit eyes underwent complete tarsorrhaphy for 7 days either with (group A, n = 14) or without (group B, n = 13) new sterile soft contact lenses. On day 7, an increase in mean corneal thickness (20.3% in group A and 17.2% in group B) was detected. New or rabbit-worn soft contact lenses were then inoculated with 10(7) colony-forming units of Pseudomonas aeruginosa or by 0.1 mL of P aeruginosa suspension. On day 9, conjunctival cultures of all eyes yielded P aeruginosa. Corneal infection developed in 11 of 14 eyes wearing new or worn, contaminated soft contact lenses. Bacterial keratitis did not develop in any of the 13 eyes inoculated with P aeruginosa suspension. Light and electron microscopy of infected eyes showed abundant polymorphonuclear neutrophils destroying the epithelium, basement membrane, and stroma. Few bacteria could be detected and only in the deep stroma. Since bacterial suspension alone caused no inflammation, soft contact lens-wear appears crucial to corneal infection in this model.

Animals↗
PubMed1990

Ocular manifestations and impression cytology of anorexia nervosa.

A prospective age- and sex-controlled study of seven anorexia nervosa patients and seven normal control patients was conducted to determine the ocular manifestations of anorexia nervosa. Slit-lamp examination of the anorexic patients demonstrated a high incidence (4/7) of multiple episcleral capillary aneurysms and subconjunctival hemorrhages. Two of seven anorexia nervosa patients had bilateral superficial punctate keratopathy. Anesthetized Schirmer tear testing demonstrated a significantly (P less than 0.005) reduced mean tear production in the anorexia nervosa group (11.3 mm) compared with the control group (22.4 mm). Masked interpretation of conjunctival impression cytology demonstrated moderate to severe conjunctival squamous metaplasia in the majority of the anorexia nervosa group (5/7) compared to normal conjunctival epithelium in the majority of the control group (5/7). Absence of nyctalopia, Bitot's spots, and xerosis, and lack of conjunctival goblet cell loss indicate that the anorexia nervosa group did not have vitamin A deficiency.

Adult↗
PubMed1990

[Initial experience with autologous conjunctiva/limbus transplantation in pterygium].

The present paper reports on the technique and results of conjunctiva/limbus transplantation in 13 eyes with primary or cicatricial pterygium (12 cases and 1 case, respectively). In all cases the pterygia were located nasally. The operation was performed by bare sclera excision, covered with a free graft from the superotemporal conjunctiva and limbus. After a mean follow-up time of 5 months there was only one recurrence. On the basis of a new understanding of limbal diseases the authors believe that conjunctiva/limbus transplantation is an encouraging and appropriate technique for ideal anatomic reconstruction and low recurrence rates in pterygia.

Adult↗
PubMed1990

[Surgical iridectomy following acute angle-closure glaucoma. A retrospective study of 107 patients].

In 69 of 107 patients with primary angle-closure glaucoma, it was possible to control intraocular pressure and visual fields by means of peripheral surgical iridectomy; in 17 of these patients topical glaucoma medication was required in addition. In 11 cases a second surgical operation other than iridectomy was necessary: 6 lensectomies for malignant glaucoma in 2 cases and lens subluxation or phacomorphic glaucoma in 4 and 5 filtering procedures. Among the 85 treated fellow eyes 68 were controlled by iridectomy alone and 17 eyes needed additional topical glaucoma medication. One case of persisting wound leakage from the corneo/scleral wound was the only complication observed in this study. The advantages and disadvantages of peripheral surgical iridectomy are compared with those of argon and neodymium: YAG iridotomies. Owing to the low rate of complications the authors apply the surgical approach as the routine technique for primary angleclosure glaucoma.

Follow-Up Studies↗