PubMed Health⌕ Search

Biomedical subjects

A H Kaufman

Publications and source records attributed to A H Kaufman.

12 recordsLinked to original sources
PubMed2000

Persistent corneal haze after excimer laser photokeratectomy in plasminogen-deficient mice.

PURPOSE: Excimer laser photorefractive keratectomy creates a nonvascular wound of the cornea. Fibrin deposition and resolution after excimer laser photokeratectomy were investigated in relation to corneal repair and restoration of clarity in mice with a genetic deficiency of plasminogen. METHODS: A Summit Apex Laser (Summit, Waltham, MA) was used to perform 2-mm, 175-pulse, transepithelial photoablations that resulted in deep stromal keratectomies. Photokeratectomy was performed on the corneas of plasminogen-deficient (Plg-/-) mice and littermate control animals. Eyes were examined for re-epithelialization and clarity throughout the 21-day observational period. Histologic sections were taken during the observational period and fibrin(ogen) was detected immunohistochemically. RESULTS: Re-epithelialization was rapid and complete within 3 days in both control and Plg-/- animals. Exuberant corneal fibrin(ogen) deposition was noted in Plg-/- mice and sparse fibrin(ogen) deposition in control mice on days 1 and 3 after injury. Fibrin(ogen) deposits resolved in control mice but persisted in Plg-/- mice (74% of eyes at 21 days; P < 0.004). Corneal opacification, scarring, and the presence of anterior chamber fibrin(ogen) occurred in plasminogen-deficient mice but not in control mice. CONCLUSIONS: Fibrin(ogen) deposition occurs during corneal wound repair after photokeratectomy. Impaired fibrinolysis in Plg-/- mice caused persistent stromal fibrin deposits that correlated with the development of corneal opacity.

Animals↗
PubMed1999

Improving comprehension and recall of information for an HIV vaccine trial among women at risk for HIV: reading level simplification and inclusion of pictures to illustrate key concepts.

A simplified version of the prototype HIV vaccine material was developed through (a) reducing reading grade level, (b) restructuring of the organization and categorization of the material, (c) adding pictures designed to emphasize key concepts, and (d) obtaining feedback on the simplified version through focus groups with the target population. Low-income women at risk for HIV (N = 141) recruited from a primary care clinic were randomly assigned to be presented the standard or the simplified version. There were no significant differences between the groups in terms of education or Vocabulary, Block Design, and Passage Comprehension scores. Women who received the simplified version had significantly higher comprehension scores immediately following presentation of the material than did women who received the standard version and were also significantly more likely to recall study benefits and risks. These findings were maintained at 3-month follow-up. Implications for informed consent are discussed.

AIDS Vaccines↗
PubMed1998

Ligneous conjunctivitis in plasminogen-deficient mice.

Ligneous conjunctivitis is a rare form of chronic pseudomembranous conjunctivitis that is associated with systemic membranous pathological changes. A probable link between plasminogen and ligneous conjunctivitis has been indicated by the recent diagnoses of plasminogen deficiency in five patients suffering from ligneous conjunctivitis. The current study reports that plasminogen-deficient mice develop conjunctival lesions indistinguishable from human ligneous conjunctivitis in both appearance and histology. Both human and mouse lesions contain acellular material rich in fibrin, and aberrant or disrupted epithelium. The incidence of lesion development in mice increases with age and is strongly influenced by genetic background. Interestingly, ligneous conjunctivitis was not observed in plasminogen-deficient mice simultaneously lacking fibrinogen. This study provides direct evidence that plasminogen deficiency is one cause of ligneous conjunctivitis and suggests that plasminogen-deficient mice may be an excellent model for the development of therapeutic strategies for the treatment of this debilitating disease.

Aging↗
PubMed1998

Healing of corneal epithelial defects in plasminogen- and fibrinogen-deficient mice.

PURPOSE: The local deposition of fibrinogen and other plasma products from tears within corneal wounds and the expression of plasminogen activator by corneal epithelial cells suggest that the coagulation and fibrinolytic systems play an important role in corneal wound healing. The authors used mouse lines deficient in plasminogen (Plg), fibrinogen (Fib), or both to elucidate the roles of these key fibrinolytic and coagulation factors in the healing of corneal epithelial defects. METHODS: Mice were anesthetized, and corneal epithelial defects (3 mm) were created with a blade. The authors conducted histologic examination and immunohistochemical analysis on the healing of injured corneas. RESULTS: The corneal epithelial defects of wild-type mice with transparent corneas healed quickly in 7 days, whereas the healing of plasminogen-deficient mice was impaired and complicated by severe and persistent inflammatory responses, the formation of retrocorneal fibrin deposits, corneal cloudiness caused by scar-tissue formation, and often stromal neovascularization. To determine whether these defects in corneal wound repair were specifically related to an impediment in fibrinolysis, corneal wound healing was compared in mice with a combined deficiency in plasminogen and fibrinogen. The loss of fibrinogen in mice lacking plasminogen resulted in the restoration of normal healing with transparent corneas in 7 days, similar to that of wild-type mice. CONCLUSIONS: These results provide direct evidence that hemostatic factors play a crucial role in corneal wound repair despite the lack of local hemorrhage. Furthermore, they demonstrate that the essential role of plasmin in corneal would healing is fibrinolysis. It prevents the adverse inflammatory responses caused by prolonged fibrin and fibrinogen deposition in injured corneas.

Afibrinogenemia↗
PubMed1996

HLA typing in patients with ocular manifestations of Stevens-Johnson syndrome.

BACKGROUND: Stevens-Johnson syndrome (SJS) is an acute, self-limited, inflammatory disorder of the skin and mucous membranes. With ocular involvement, SJS has been associated with the class I human leukocyte antigen (HLA)-Bw44. This study examined HLA class II associations in patients with SJS with ocular involvement to help identify possible molecular genetic mechanisms underlying disease susceptibility/resistance. METHODS: Twenty-three white patients with ocular complications secondary to SJS had HLA class II typing performed using polymerase chain reaction-based molecular techniques. Genotype frequency was compared with results obtained from 175 control subjects. RESULTS: HLA-DQB1*0601 was present in four (17%) patients with SJS and in five (3%) control subjects (P < 0.05; relative risk = 7.2). There was no association with HLA-DQB1*0301, which previously has been been strongly associated with recurrent erythema multiforme. None of the class II antigens tested appeared to offer a protective effect against the development of disease. CONCLUSION: HLA-DQB1*0601 was found in a significantly disproportionate number of white patients with SJS and ocular complications. The presence of this allele may confer an increased risk for the development of SJS with ocular complications and provides further evidence for an underlying immunogenetic susceptibility to the development of this disease.

Adult↗
PubMed1996

Conjunctival epithelial cells can resurface denuded cornea, but do not transdifferentiate to express cornea-specific keratin 12 following removal of limbal epithelium in mouse.

Limbal stem cell deficiency contributes to recurrent corneal epithelial defects. We examined whether the conjunctival epithelium can transdifferentiate to corneal epithelium following surgically induced limbal stem cell deficiency. Mice were anesthetized by intraperitoneal injection of sodium pentobarbital. Partial or total epithelial removal was produced with a no. 69 Beaver blade under a dissecting microscope. The wounds were allowed to heal for 0-28 days, and the mice were examined every other day to evaluate re-epithelialization. Corneas were then subjected to histological, immunohistochemical studies and Western blot analysis with epitope-specific anti-keratin 12 antibodies. Partial epithelial defects re-epithelialized within 2 days and were normal in appearance and expressed cornea-specific keratin 12. In eyes with limbal deficiency, re-epithelialization progressed more slowly and was characterized by opacification; epithelial closure usually occurred by the 7th day. This epithelium differed from normal corneal epithelium in basic morphology, cell shape, and the presence of goblet cells at 2 weeks after injury. The epithelium at the center of injured corneas with total defect at 4 weeks had cornealike morphology and was devoid of goblet cells. These epithelial cells derived from conjunctiva did not express the cornea-specific keratin 12 as determined by immunohistochemistry, Western blot analysis and in situ hybridization. As evidenced by differences in morphology and the expression of cornea-specific keratin 12, conjunctival transdifferentiation does not occur in conjunctical overgrowth after the removal of limbal epithelium.

Amino Acid Sequence↗
PubMed1996

Healing corneas express embryonic fibronectin isoforms in the epithelium, subepithelial stroma, and endothelium.

The cornea is a simple, nonvascularized structure, advantageous for studying the molecular components of epithelial and stromal wound repair. Fibronectin (Fn), of uncertain source and composition, accumulates in healing corneas. We postulated that local synthesis of Fn occurs, as exogenous plasma/tear-derived Fn, which lack the embryonic EIIIA and EIIIB segments, have no consistent beneficial effect on healing. Two contrasting corneal wounds were examined by in situ hybridization: a wound of the anterior stroma, basement membrane, and epithelium (anterior excimer laser keratectomy) and a superficial wound restricted to the epithelium that preserved the basement membrane (mechanical scrape). Both wounds heal without scarring. In normal corneas, only the endothelium had detectable Fn mRNA, containing the V and EIIIB domains, sporadically and at low levels. After anterior keratectomies, extensive expression of Fn mRNA occurred in a specific distribution that changed during the phases of healing. Before re-epithelialization (days 1 and 2) V+, EIIIA+, and EIIIB+ isoforms were diffusely found in stromal cells under and adjacent to the wound. After re-epithelialization (days 3 to 42) and reconstitution of laminin in the regenerating basement membrane zone, V+, EIIIA+, and EIIIB+ isoform synthesis was largely restricted to subepithelial stromal cells at the epithelial/stromal interface. In addition, the corneal epithelial cells focally expressed Fn mRNA. The endothelium showed increased levels of V+, EIIIA+, and EIIIB+ Fn mRNA in open and recently re-epithelialized wounds. At 12 weeks after keratectomy, Fn mRNA expression returned to control levels. In contrast, scrape wounds had only a modest increase of stromal and endothelial Fn mRNA (EIIIA+, EIIIB+, and V+) during the first 7 days and no evidence of epithelial Fn synthesis. Embryonic Fn isoforms are synthesized transiently by the cornea in response to even the most superficial wounds and are likely to be relevant to corneal healing and restoration of structure without scar formation.

Animals↗
PubMed1995

Expression of collagens I, III, IV and V mRNA in excimer wounded rat cornea: analysis by semi-quantitative PCR.

A semi-quantitative polymerase chain reaction (PCR) methodology was used to evaluate the kinetic changes occurring in collagens I, III, IV and V mRNA in rat cornea following excimer laser keratectomy. cDNA was synthesized from RNA extracted from rat cornea at various times following excimer laser photoablative keratectomy. Collagen cDNA sequences were subsequently amplified using specific sets of oligonucleotide primers. Competitive PCR amplification was carried out using an internal standard so that a semi-quantitative analysis of message for synthesis of collagen types I, III, IV and V could be performed and time course dynamics of message for these collagens studied. There was a biphasic increase in the levels of collagens III, IV and V mRNA following excimer laser keratectomy. Collagen I mRNA levels demonstrated a more sustained increase and were still elevated at 6 weeks following wounding. Collagens IV and V mRNA showed the largest increase with an approximate three fold increase over controls between 4 days and 1 week. Our results demonstrate that upregulation of stromal collagens I, III, and V mRNA and basement membrane collagen IV mRNA occurs in rat cornea following excimer laser keratectomy.

Animals↗
PubMed1993

Cataract extraction in patients with pars planitis.

BACKGROUND: The authors analyzed the results of cataract surgery performed on patients with pars planitis from January 1985 through August 1992. METHODS: One hundred twenty-six patients with pars planitis were evaluated and treated during this period. Cataracts that warranted surgery developed in 12 patients (18 eyes) from this tertiary referral population. These 12 patients were evaluated with respect to pars planitis duration, systemic disease association, treatment regimens, macular and disc pathology, and final visual result. RESULTS: The average final visual acuity of these 18 eyes was 20/38, and 83% of the patients achieved a final visual acuity better than or equal to 20/40. The factors that limited visual recovery to this level were primarily macular and optic nerve pathology (cystoid macular edema [CME], macular epiretinal membrane, and optic atrophy). Control of inflammation required regional steroids in all patients, systemic steroids in ten patients, and immunosuppression in four patients. Posterior chamber lens implantation accompanied the surgery in 14 eyes (10 patients). Recurrent episodes of inflammation in two patients (3 eyes) resulted in accumulation of deposits on the posterior chamber intraocular lens (IOL) surface. Deposits were removed by a YAG laser lens "polishing" session. CONCLUSION: Absolute control of inflammation in patients with pars planitis through a stepladder approach may reduce the incidence of cataract development, and can certainly improve visual rehabilitation after cataract extraction. Implantation of a posterior chamber lens can be well tolerated in selected cases.

Adult↗
PubMed1984

Purine nucleotide reutilization by human lymphoblast lines with aberrations of the inosinate cycle.

A purine nucleotide (inosinate) cycle is demonstrated with human lymphoblasts. The lymphoblast requires approximately 50 nmol of purine/10(6) cell increment. When the inosinate cycle is interrupted by the genetic, severe deficiency of either or both purine nucleoside phosphorylase (PNP) or hypoxanthine phosphoribosyltransferase (HPRT), purine accumulates in the culture medium as inosine, guanosine, deoxyinosine, and deoxyguanosine (PNP deficiency or PNP, HPRT deficiency) or hypoxanthine and guanine (HPRT deficiency). This accumulation represents an additional 25 to 32 nmol of purine which must be synthesized per 10(6) cell increment. PNP-deficient lymphoblasts have PPRibP contents characteristic of normal lymphoblasts, about 20 to 25 pmol/10(6) cells. HPRT-deficient lymphoblasts have four times higher PPRibP contents. The lymphoblast deficient for both PNP and HPRT has only a marginal elevation of PPRibP content, 1.5 times normal values. The elevated PPRibP content of HPRT-deficient cells reflects the efficient, unilateral reutilization of the ribose moiety of purine ribonucleotides and is not a cause of purine overproduction. Purine overproduction characterizing PNP-deficient lymphoblasts appears similar to overproduction from deficiency of HPRT, i.e. a break in the inosinate cycle rather than overactive de novo purine synthesis.

B-Lymphocytes↗