Biomedical subjects

H Lewis

Publications and source records attributed to H Lewis.

At least 73 records · Page 4Linked to original sources

PubMed1995

Synthesis and NMR of RNA with selective isotopic enrichment in the bases.

Efficient syntheses of pyrimidine and purine nucleosides and nucleotides with selective 13C enrichment in the base moieties are described. Uridine and cytidine are labeled at position C6 and adenosine and guanosine are labeled at position C8. The selectively labeled nucleosides were converted to nucleoside triphosphates and used with in vitro transcription to synthesize labeled RNA. Isotope-edited 12C and 13C sub-spectra of a omega 1-1/2-X-filtered NOESY experiment are demonstrated to be useful for making resonance assignments and for deriving structural information in large (> 20 nt) RNA molecules. The labeled RNAs also allow heteronuclear J-couplings and relaxation parameters to be measured without complications from 13C-13C J-couplings.

Adenine↗

PubMed1995

Vitrectomy techniques in late-stage Coats'-like exudative retinal detachment.

Retinal telangiectasia is the hallmark of Coats' disease. In the late stages, leakage from these abnormal vessels can result in a total, bullous exudative retinal detachment with cholesterol-laden subretinal fluid. Secondary angle-closure glaucoma may result in a blind and painful eye which may require enucleation or evisceration. Surgical reattachment of the retina and destruction of the retinal telangiectasia may preserve these eyes. We have found that vitrectomy, internal drainage of subretinal fluid and cholesterol, direct treatment of the retinal telangiectasia with intraocular diathermy and intravitreal gas or silicone oil injection are effective surgical techniques for salvaging these severely damaged eyes.

Adult↗

PubMed1995

Family influences on coping processes in children and adolescents with sickle cell disease.

Examined the contribution of parenting and family variables to the general coping processes of 39 children and adolescents with sickle cell disease (SCD). In home interviews, parents reported on their child's health history, the coping suggestions they make to their children, their own coping strategies, and family cohesion. Children rated their general coping strategies and level of hope. Partial support was obtained for each of the three models of family influences tested in this study. After accounting for the effects of age, gender, family structure, and type of SCD, children's hope was positively associated with active coping suggestions by parents. Children's active coping was associated with a cohesive family environment, and avoidance coping was predicted by less parental use of restructuring coping, and greater parental use of active coping strategies. Taken together, this study provides evidence for the influence of parental coaching and modeling and the family environment on coping processes in children with SCD.

Adaptation, Psychological↗

PubMed1995

A late, fatal complication of a high energy thermal injury to the scalp.

Marjolin's ulcer is an uncommon condition in which malignant transformation occurs in a chronic inflammatory focus. It was originally described in association with a thermal injury, however, its occurrence with protean chronic inflammatory foci has been described. We report the occurrence of and aggressive squamous carcinoma 3 decades after a high voltage electric mark injury to the scalp. This is the first such case described in the literature. The case supportively highlights the role of chronic inflammation and sepsis in epidermal scar cancer development, and it underlines the importance of appropriate wound management initially and expeditious treatment of sepsis and resistant skin ulceration because the malignant behavior of these tumors is aggressive and unpredictable.

Carcinoma, Squamous Cell↗

PubMed1994

Intraoperative fibrinolysis of submacular hemorrhage with tissue plasminogen activator and surgical drainage.

PURPOSE: This pilot study determined the safety and efficacy of intraoperative pharmacologic lysis of recent submacular hemorrhage with tissue plasminogen activator followed by surgical drainage of the unclotted blood in patients with age-related macular degeneration. METHODS: In a prospective study, 24 consecutive eyes with recent (< 14 days old) submacular hemorrhage secondary to age-related macular degeneration and good visual acuity before development of submacular hemorrhage were treated with vitrectomy, subretinal injection of tissue plasminogen activator, and removal of the liquefied blood. Patients were followed up for at least six months (mean, 14 months). RESULTS: Twenty eyes (83%) had improved visual acuity after surgery, and eight eyes (33%) attained visual acuity of 20/200 or better. In a subset of 16 eyes with submacular hemorrhage of seven days duration or less, eight (50%) attained visual acuity of 20/200 or better. Factors associated with poor visual outcome included submacular hemorrhage with duration greater than seven days (P < .001), the presence of hemorrhagic pigment epithelial detachment (P = .04), and massive subretinal hemorrhage (P = .04). CONCLUSIONS: Tissue plasminogen activator thrombolysis may be a valuable adjunct to the surgical treatment of select patients with submacular hemorrhages secondary to age-related macular degeneration.

Aged↗

PubMed1994

Metastatic choroidal abscess and choroidal neovascular membrane associated with Staphylococcus aureus endocarditis in a heroin user.

BACKGROUND: A 44-year-old man who was an intravenous heroin user developed multiple septic emboli, including a choroidal abscess in the macula and foot and skin infection after Staphylococcus aureus endocarditis. METHODS: Prompt administration of systemic oxacillin and gentamicin was prescribed for the endocarditis. RESULTS: One week after septic embolization to the choroid, a subfoveal, poorly-defined choroidal neovascular membrane with retinochoroidal anastomosis was noted at the site of active choroidal infection. CONCLUSION: Systemic antibiotic therapy successfully eradicated the choroidal infection, prevented progression to endophthalmitis, and improved visual acuity.

Abscess↗

PubMed1994

Cooperativity between two NF-kappa B complexes, mediated by high-mobility-group protein I(Y), is essential for cytokine-induced expression of the E-selectin promoter.

Cytokine-induced expression of the E-selectin gene requires the promoter binding and interaction of the transcription factors NF-kappa B and ATF. Here we have further analyzed the E-selectin promoter and revealed an additional region (nucleotides -140 to -105 [-140/-105]) which is essential in controlling promoter activation by cytokines. We identified high-mobility-group protein I(Y) [HMG-I(Y)] interacting specifically at two sites within this region. We noted that one of the HMG-I(Y)-binding sites overlaps a sequence element (-127/-118) diverging at only one position from the NF-kappa B consensus binding sequence. This led us to ask whether the -127/-118 element represents a second functional NF-kappa B-binding site within the E-selectin promoter. Using specific antisera, we show that p50, p65, and, interestingly, RelB are components of the complex interacting at this site. Mutational analysis of the -127/-118 NF-kappa B site indicates that both NF-kappa B and HMG-I(Y) binding at this site are essential for interleukin-1 induction of the promoter. We demonstrate that the binding affinity of the p50 subunit of NF-kappa B to both NF-kappa B sites within the E-selectin promoter is significantly enhanced by HMG-I(Y). In addition, an essential role for cooperative interaction between the two NF-kappa B complexes is shown by the requirement for both NF-kappa B sites to mediate E-selectin promoter activation by interleukin-1 and p50/p65 expression. We conclude that HMG-I(Y) mediates binding of a distinct NF-kappa B complex at two sites within the E-selectin promoter. Furthermore, a unique cooperativity between these NF-kappa B complexes is essential for induced E-selectin expression. These results suggest mechanisms by which NF-kappa B complexes are involved in specific gene activation.

Base Sequence↗

PubMed1994

Interference by Parvolex with chloride estimation by the Ag/AgCl method.

We demonstrate significant interference by Parvolex (acetylcysteine) with the Ag/AgCl method for chloride estimation. A study of four patients who had taken a paracetamol overdose and been treated with Parvolex implied this interference, and an in vitro study confirmed it. The interference was shown to decline upon storage of the serum at a similar rate in both the patient and in vitro studies. Suggested mechanism for these phenomena are given.

Blood Glucose↗

PubMed1994

Decreased T cell reactivity to trypsinized group A, type M22 streptococci in psoriasis.

The proliferative responses of peripheral blood mononuclear cells from patients with guttate and chronic plaque psoriasis to streptococcal M protein were investigated using whole and trypsinized group A M22-positive streptococci. Peripheral blood mononuclear cell responses to whole type M22 group A streptococci were significantly increased in guttate, but not chronic plaque, psoriasis patients compared to 17 non-psoriatic controls (p < 0.05; n = 17). A significant reduction of this response was observed in both guttate (p < 0.001; n = 17) and chronic plaque (p < 0.01; n = 27) psoriatic patients, but not in the control group, after repeated trypsinization to remove M protein from the streptococci. Furthermore, the difference between the peripheral blood mononuclear cell response to untrypsinized and trypsinized streptococci was significantly greater in the guttate patients than in the controls (p < 0.02). This preliminary study has shown an increased reactivity of T lymphocytes with specificity for trypsin-sensitive protein expressed by type M22 streptococci in the peripheral blood of patients with psoriasis.

Adolescent↗

PubMed1993

Relaxing retinotomy with silicone oil or long-acting gas in eyes with severe proliferative vitreoretinopathy. Silicone Study Report 5. The Silicone Study Group.

In the Silicone Study, 117 of 404 eyes (29%) with severe proliferative vitreoretinopathy (> or = C-3, full-thickness retinal folds in three or more quadrants) enrolled in the study were treated with vitrectomy, underwent a relaxing retinotomy, and were randomly assigned to treatment with long-acting gas or silicone oil. Forty-six eyes (20%) had undergone no previous vitrectomy (group 1); 71 eyes (42%) had undergone previous vitrectomy (group 2) with intraocular gas tamponade (P < .001). Group 1 eyes not undergoing retinotomy had better anatomic (six months) and visual (six and 24 months) outcomes and less hypotony (six months) than eyes that did regardless of tamponade (P < .05). For eyes undergoing retinotomy, silicone oil decreased the likelihood of hypotony (six months, P < .05). These differences were not found in group 2 eyes. We conclude that eyes undergoing a vitreous operation for the first time for the treatment of proliferative vitreoretinopathy can in most instances be successfully treated by conventional techniques without the need for relaxing retinotomy. Retinotomy may be required more often in patients undergoing repeat vitreous surgery for proliferative vitreoretinopathy, in which case both silicone oil and long-acting perflouropropane gas appear to be equally effective.

Eye Diseases↗

PubMed1993

The use of perfluorocarbon liquids in the repositioning of posteriorly dislocated intraocular lenses.

PURPOSE: Removal of intraocular lenses (IOLs) dislocated into the vitreous cavity can be hazardous and result in severe complications and visual loss. Recognizing limitations in current management, the authors developed a new, safer surgical technique to reduce intraoperative and postoperative complications. METHODS: The authors report eight eyes of eight patients with posteriorly dislocated IOLs in which perfluorocarbon liquids were injected into the eye after vitrectomy to float the IOL off the retina. The IOL haptics were repositioned in the residual capsular bag or ciliary sulcus, and the positioning holes of the optic were sutured to the sclerotomies under a scleral flap. RESULTS: With a minimum follow-up of 8 months (average, 12 months), all eight eyes improved in Snellen visual acuity, and six of them achieved a final Snellen visual acuity of 20/40 or better. Complications did not occur in any of the eight eyes. Preoperative cystoid macular edema resolved in three of four eyes, and the retina has remained attached in the one eye with a preoperative retinal detachment. CONCLUSION: Application of vitreoretinal microsurgical techniques and the use of liquid perfluorocarbons allow for the safer management of eyes with posteriorly dislocated IOLs.

Aged↗

PubMed1993

Group A streptococcal antigen-specific T lymphocytes in guttate psoriatic lesions.

A strong association exists between guttate psoriasis and group A, beta-haemolytic streptococcal infections. To demonstrate the presence of streptococcal-specific T cells in psoriatic skin, T-cell lines (TLs) were established from biopsies of lesions from five patients with guttate psoriasis, and compared with TLs from five patients with eczema, five with lichen planus, two with pityriasis rosea and three with nickel contact dermatitis. TLs from purified protein derivative (PPD)-induced delayed hypersensitivity sites in three normal individuals were also studied. All five of the psoriatic TLs responded in a proliferation assay to heat-killed isolates of group A streptococci, compared with only one eczema, two lichen planus and one pityriasis rosea. The response of one nickel contact dermatitis and two PPD TLs to group A streptococci was markedly less than to nickel and PPD, respectively. One of the psoriatic TLs was cloned in the presence of type 5 streptococcal M protein. The nine clones obtained were all CD3+, CD4+, CD45RO+, TCR alpha, beta+, gamma, delta-. However, they were all unreactive with antibodies to TCR V beta 5, 6, 8 or 12. Eight of the nine clones reacted, to a varying extent, to one or two of three preparations of group A streptococci expressing different M proteins. The streptococcal response of four consistently reactive clones from this patient was HLA-DR-restricted and inhibited by anti-HLA-DR antibody in a dose-dependent manner. On stimulation these four clones secreted high levels of gamma-interferon and detectable levels of IL-2, IL-10 and granulocyte/macrophage colony stimulating factor (GM-CSF) depending upon the nature of the stimulus, but no IL-4 or TNF-alpha production was detected. This study has demonstrated, for the first time, that T lymphocytes specific for group A streptococcal antigens can be consistently isolated from guttate psoriatic lesions. The role of streptococcal-specific T cells in the pathogenesis of psoriasis remains to be determined.

Antigens, Bacterial↗

PubMed1992

Macular phototoxicity caused by fiberoptic endoillumination during pars plana vitrectomy.

Three cases of retinal phototoxicity were caused by light from the endoilluminator used in vitrectomy. Preoperative clinical examination, color photography, and fluorescein angiography in all three cases failed to disclose retinal pigment epithelial changes. Postoperative clinical findings, photographs, and fluorescein angiograms are highly suggestive of the presence of retinal phototoxicity. The characteristics of these lesions and surgical conditions implicate the endoilluminator as the source of photic injury. The macular lesions were noted within one week of the surgical procedure, measured between 2 and 5 disk diameters in size, involved the fovea in two eyes, and resulted in marked decrease in visual acuity in two of three eyes, with persistence in one eye. Initially, whitening of the outer retina was present, but was replaced by pigmentary mottling at the level of the retinal pigment epithelium within a few weeks. Preventive measures to avoid macular phototoxicity associated with vitrectomy are discussed.

Adult↗

PubMed1992

Noncontact transscleral neodymium-YAG laser photocoagulation of the pigmented rabbit retina.

We studied the applicability of transscleral delivery of noncontact neodymium-YAG laser in its free-running mode (10 milliseconds) in creating chorioretinal lesions in 16 rabbits. After the laser was applied, the eyes were studied by indirect ophthalmoscopy, light microscopy, and electron microscopy. Lesions generated with low-energy and defocus settings were characterized by intact sclera, variable clumping of the pigmented choroidal lamellae, destruction of choriocapillaris, and loss of the retinal pigment epithelium. In the central region of laser exposure, vacuolization of the retinal pigment epithelium and outer retina were observed. No scleral changes were noted. In contrast with lesions produced with high-energy and/or high-defocus settings, these lesions were produced without hemorrhagic phenomena or breaks in the neurosensory retina. These data demonstrate that noncontact transscleral neodymium-YAG photocoagulation is capable of very localized, selective destruction of the retina and choroid and deserves further study.

Animals↗

PubMed1992

Vitrectomy for diabetic macular traction and edema associated with posterior hyaloidal traction.

Pars plana vitrectomy with separation of the posterior hyaloid was performed in 10 eyes with diabetic macular edema and traction associated with a thickened and taut premacular posterior hyaloid. Nine of the 10 eyes had previous macular photocoagulation. Preoperative fluorescein angiography showed a deep and diffuse pattern of leakage in the macula. Intraoperatively, the attached and thickened posterior hyaloid was lifted and separated from the retina. Postoperatively, vision improved in nine eyes. The macular traction and edema resolved in eight eyes and decreased in two. Complications included a vitreous hemorrhage, a rhegmatogenous retinal detachment, cataract formation, and a mild epimacular membrane, each occurring in one eye. Vitreous surgery can improve the visual prognosis of some eyes with diabetic macular traction and edema associated with a thickened and taut posterior hyaloid.

Adult↗

PubMed1992

Management of giant retinal tears without scleral buckling. Use of radical dissection of the vitreous base and perfluoro-octane and intraocular tamponade.

The introduction of intraoperative perfluorocarbon liquids in the management of giant retinal tears has allowed exact anatomic reapposition of the retina and the giant retinal tear. Therefore, the authors managed 11 eyes with giant retinal tears and no proliferative vitreoretinopathy without scleral buckling. Maximum removal of the basal vitreous gel was performed in all cases, and perfluoro-octane was used intraoperatively to unfold the inverted posterior flap and reattach the retina completely. Endophotocoagulation was applied to the edges of the tear and perfluoropropane or silicone oil was used as an intraocular tamponade. Although 1 eye required reoperation for a redetachment from posterior proliferative vitreoretinopathy, all retinas were reattached with final visual acuity of 5/200 or better in 9 eyes. Eight additional major procedures were necessary in seven eyes: removal of silicone oil in four (with removal of perisilicone proliferation in three), repeat vitrectomy and membrane removal with photocoagulation twice in one eye, cataract extraction in one eye, and removal of a macular pucker in one eye. Four eyes required postoperative fluid-gas exchange and three eyes had tissue plasminogen activator injections into the anterior chamber for postoperative fibrin reactions.

Adolescent↗

PubMed1992

Treatment of dislocated crystalline lens and retinal detachment with perfluorocarbon liquids.

Removal of a crystalline lens dislocated into the vitreous cavity can be hazardous, particularly in the presence of a retinal detachment. Hard pieces of nuclear material may be difficult to extract and may repeatedly fall onto the retina when emulsification is attempted in the vitreous cavity. Cases involving four eyes with dislocated crystalline lens and rhegmatogenous retinal detachment, into which liquid perfluorocarbon was injected after vitrectomy to float the dislocated lens material off the retina and reattach the retina, are reported. The dislocated lens was removed while floating on the perfluorocarbon liquid, which also provided a cushion that prevented dropped fragments of lens from traumatizing the retina. In all four cases, surgery was not associated with complications and resulted in improvement in visual acuity and retinal reattachment.

Adult↗

PubMed1991

Decrease in the risk of bilateral acute retinal necrosis by acyclovir therapy.

We reviewed the course of 54 patients who had unilateral acute retinal necrosis at initial examination. Thirty-one patients were treated with acyclovir, whereas 23 were not. Of the 31 patients treated with acyclovir, 27 (87.1%) had fellow eyes that remained disease-free throughout a median follow-up of 12 months. Of the 23 patients not treated with acyclovir, seven (30.4%) had fellow eyes that remained disease-free throughout a median follow-up of 11 months. Survival analysis indicated that the fellow eyes of the group of patients treated with acyclovir were more likely to remain disease-free than the fellow eyes of the group not treated with acyclovir (P = .0013). Two years after initial onset, the proportion of fellow eyes that remained disease-free was 75.3% for the group treated with acyclovir and 35.1% for the group not treated with acyclovir. These results suggest that acyclovir treatment reduces the risk of involvement of the fellow eye in patients with acute retinal necrosis.

Acyclovir↗