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Biomedical subjects

V Lee

Publications and source records attributed to V Lee.

At least 55 records · Page 3Linked to original sources
PubMed2001

Strabismus surgery in congenital third nerve palsy.

BACKGROUND: Congenital third nerve palsy is a rare condition that usually presents with a large-angle incomitant strabismus and is often associated with ptosis and amblyopia. METHODS: We present the results of strabismus surgery in seven consecutive patients. RESULTS; All the palsies developed before the age of 6 months and the age at surgery ranged from 3 to 24 years. The operations performed included horizontal recti resection/recession (7), supra-placement of the insertions (6), superior oblique weakening (4) and traction sutures (4). The preoperative and postoperative horizontal deviations consisted of seven exotropias and one esotropia due to a combined sixth and partial third nerve palsy. The preoperative vertical deviation consisted of 7 hypotropias and one hypertropia; postoperatively, 5 remained hypotropic and 2 were hypertropic. All patients underwent ptosis surgery. CONCLUSION: Patients with congenital third nerve palsy often achieve reasonable cosmesis with strabismus and ptosis surgery.

Adolescent↗
PubMed2001

Functional assessment of older adults in an emergency department.

The fast paced nature of emergency medicine often precludes assessment of patient functioning which may have significant consequences for geriatric patients including falls, functional decline and/or hospital re-admission. A rehabilitation consultation service to a hospital emergency department was implemented based on recommendations in the literature that functional assessments and a multidisciplinary approach be used with older adults. A systematic method of targeting and assessing elderly at-risk patients included a safety checklist and a comprehensive functional assessment tool. An observational study of 80 patients receiving functional assessments from rehabilitation professionals is described. Patients with high levels of disability or who lived alone prior to the emergency visit were more likely to be admitted to hospital. This study supports using multidisciplinary efforts and comprehensive functional assessments in emergency departments to guide decision-making about discharge outcome and planning for the health care needs of elderly patients.

Aged↗
PubMed2001

Measuring quality of care with an inpatient elderly population. The geriatric resource nurse model.

Nurses provide health services to an increasing number of older adults in acute care settings. Acute care nurses are committed to giving patients the highest quality care while recognizing the importance of delivering care in a cost-effective manner. In this study, a unit-based, nurse-centered geriatric program is evaluated. The program is designed to enhance the knowledge and skill of staff nurses in providing care to elderly patients. Both quantitative and qualitative methods are used to assess geriatric resource nurses' (GRNs) influence on quality and cost outcomes of the elderly participants. Patients age 65 years and older were randomly selected from two general medical units of a major academic tertiary care center in the southeastern United States. Data were collected during an 18-month period in 1996 and 1997. A total of 129 participants provided data for quantitative analysis. A subset of 34 participants (17 from the unit where GRNs were on staff and 17 from a control unit) was interviewed about their experience during hospitalization. This information was analyzed for common themes and trends using appropriate qualitative techniques. Demographic variables and common measures of illness severity and complexity showed comparable patient populations on the two units. However, results of quantitative analyses indicated significant differences between groups on admission for several of the health status measures. Participants on the unit without GRNs were found to have more problems with pain, incontinence, and mobility. Administrative measures showed the number of patients readmitted to the hospital within 31 days of discharge and the length of stay associated with this initial readmission were significantly lower on the unit with GRNs. The use of vest-type physical restraints was also less frequent on this unit. Elderly patients in both groups indicated they have special needs related to normal aging changes and chronic illnesses, resulting in higher levels of fragility and decreased energy reserves. They identified specific functional areas for which help was needed. These include assistance with bathing, eating, sleeping, mobility, and elimination. Fewer participants on the intervention unit reported decline in activities of daily living (ADL) function during hospitalization than did control participants. Participants in both groups stressed the importance of nurses' demonstrating understanding and caring when working with older individuals.

Aged↗
PubMed2001

Aminoguanidine and ramipril prevent diabetes-induced increases in protein kinase C activity in glomeruli, retina and mesenteric artery.

This study investigated the effects of insulin therapy, inhibition of advanced glycation end-product formation with aminoguanidine and angiotensin-converting enzyme inhibition with ramipril on diabetes-related increases in protein kinase C (PKC) activity in the streptozotocin-diabetic rat. PKC activity in the glomeruli, retina and mesenteric artery was increased by 1.5-2-fold after induction of diabetes, and this increase was maintained over 24 weeks. Treatment with insulin at 2 units or 6 units per day attenuated glomerular PKC in proportion to the level of glycohaemoglobin after 4 weeks of diabetes (r=0.68, P<0.0001). The higher dose of insulin prevented the diabetes-related increase in glomerular PKC activity, although blood glucose levels were not normalized. After 8 weeks of diabetes, ramipril completely prevented the diabetes-related increases in PKC activity in the glomeruli, retina and mesenteric artery. By contrast, aminoguanidine treatment resulted in no inhibition of glomerular PKC activity, partial inhibition of retinal PKC activity and complete inhibition of mesenteric artery PKC activity. After 24 weeks of diabetes, both aminoguanidine and ramipril prevented the diabetes-related increases in PKC activity in all three tissues, in parallel with suppression of albuminuria by both agents. Aminoguanidine also prevented diabetes-related increases in retinal permeability at 16 weeks. These results suggest that the organ-protective effects of insulin, aminoguanidine and ramipril in diabetes may be mediated, at least in part, through the differential inhibition of PKC activity in various tissues.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

The roles of matrix molecules in mediating chondrocyte aggregation, attachment, and spreading.

The most abundant macromolecules in cartilage are hyaluronan, collagen, aggrecan, and link protein, which are believed to play roles in maintaining a unique three-dimensional network for a functional joint. This study was designed to investigate the roles of the major extracellular molecules in mediating chondrocyte-matrix interactions. We employed specific approaches to remove components individually or in combination: hyaluronan was digested with hyaluronidase; type II collagen was digested with collagenase; aggrecan expression was inhibited with antisense and beta-xyloside approaches; and link protein expression was inhibited with antisense oligonucleotides. Digestion of hyaluronan induced chondrocyte attachment to tissue culture plates, collagen-coated plates, and fibroblast-like chondrocyte cultures, and induced chondrocyte aggregation. Treated chondrocytes exhibited a fibroblast-like morphology, and the effects of hyaluronidase were dose-dependent. Conversely, the effect of collagenase on chondrocyte adhesion and aggregation was far less pronounced. Treatment with Arg-Gly-Asp peptide inhibited chondrocyte-collagen interaction. Chondrocyte attachment was enhanced by antisense oligonucleotides complementary to aggrecan and link protein and by beta-xyloside treatment. Nevertheless, hyaluronan seems to predominate over the other molecules in mediating chondrocyte-matrix interactions.

Animals↗
PubMed2000

Tandem repeats are involved in G1 domain inhibition of versican expression and secretion and the G3 domain enhances glycosaminoglycan modification and product secretion via the complement-binding protein-like motif.

The large aggregating chondroitin sulfate proteoglycans, including aggrecan, versican (PG-M), neurocan, and brevican, are characterized by N-terminal and C-terminal globular (or selectin-like) domains known as the G1 and G3 domains, respectively. For this study, we generated a series of expression constructs containing various combinations of chicken versican/PG-M domains and a leading peptide of link protein in order to examine the roles of the G1 and G3 domains in versican function. In transfection studies, we observed that the presence of the G1 domain was sufficient to inhibit product secretion, while the G3 domain enhanced this process. We also demonstrated that the G1 domain inhibited the attachment of glycosaminoglycan chains to the core proteins, while the G3 domain enhanced this process. Further studies revealed that inhibition of secretion by G1 was mediated by its two tandem repeats, while G3's promotion of glycosaminoglycan chain attachment was apparently dependent on G3's complement-binding protein (CBP)-like motif. The modulatory effects of these two molecular domains may contribute to versican's biological activities.

Animals↗
PubMed2000

Angiotensin converting enzyme inhibition reduces retinal overexpression of vascular endothelial growth factor and hyperpermeability in experimental diabetes.

AIMS/HYPOTHESIS: Angiotensin converting enzyme (ACE) inhibition has been recently suggested to have retinoprotective actions in diabetic patients but the mechanism of this effect is not known. In vitro, angiotensin II stimulates expression of vascular endothelial growth factor (VEGF), a permeability-inducing and endothelial cell specific angiogenic factor which has been implicated in the pathogenesis of diabetic retinopathy in humans and in experimental animals. We sought to determine the effects of ACE inhibition on retinal VEGF expression and permeability in experimental diabetic retinopathy. METHODS: Streptozotocin-induced diabetic rats and control animals were assigned at random to receive ACE inhibitor treatment or vehicle. At 24 weeks the retinal VEGF protein gene expression was assessed by northern blot analysis and in situ hybridisation. Retinal permeability to albumin was measured using a double isotope technique. RESULTS: Experimental diabetes was associated with cell specific two to fourfold increase in retinal VEGF protein gene expression (p < 0.01) and a 2-fold increase in retinal vascular permeability to albumin (p < 0.01). The localization of VEGF expression in the retina was not altered in animals with experimental diabetes. Angiotensin converting enzyme inhibitor treatment of diabetic rats reduced diabetes-associated changes in VEGF gene expression and vascular permeability. CONCLUSION/INTERPRETATION: These findings implicate the renin-angiotensin system in the VEGF overexpression and hyperpermeability which accompany diabetic retinopathy and provide a potential mechanism for the beneficial effects of ACE inhibition in diabetic retinal disease.

Angiotensin II↗
PubMed2000

Exposure of primary orbital implants in postenucleation retinoblastoma patients.

PURPOSE: To determine significant factors influencing the exposure of primary orbital implants in patients with retinoblastoma. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: One hundred nine consecutive patients (110 sockets) who had undergone enucleation for retinoblastoma from January 1993 to December 1997. METHODS: Two patients with recurrence of orbital retinoblastoma were excluded from further analysis, leaving 107 patients (108 sockets). The parameters analyzed included the patient's age; gender; ocular diagnosis; surgeon; type, covering, and size of the implant; the use of chemotherapy or radiotherapy; and the timing of these treatments in relation to enucleation. Study patients were divided into two main groups: the "treated group"-patients who had undergone adjuvant external beam radiotherapy or chemotherapy, and the "untreated group"-patients had undergone enucleation with or without cryotherapy, laser thermotherapy, or brachytherapy to the index or fellow eye. The following additional parameters were noted in the patients with exposed implants: time to exposure from date of enucleation and treatment of exposure. MAIN OUTCOME MEASURE: Exposure of orbital implants. RESULTS: There were two exposures caused by orbital recurrence of retinoblastoma. The rate of nontumor recurrence exposure was 28% (30 of 108). The median time to exposure was 136 days (range, 1-630 days). There were 18 exposures (35%,18 of 51) in the treated group, with a 34% exposure rate (13 of 38) in the chemotherapy group. The exposure rate was 21% (12 of 57) in the untreated group. The rates of exposure according to implant were: Vicryl mesh-wrapped hydroxyapatite (2 of 18, 11%), Medpor (8 of 13, 53%), plain polymethylmethacrylate (PMMA) (4 of 50, 8%), Mersilene-wrapped PMMA (9 of 17, 53%) and Castroviejo (7 of 10, 70%). Eight of the exposures (27%) were managed conservatively; the remainder required surgical repair. CONCLUSIONS: Results suggested that implant type and covering (P = 0.000) had a highly significant effect on the rate of exposure in postenucleation retinoblastoma patients. There was no statistical evidence that age, gender, ocular diagnosis, surgeon, size of the implant, or radiotherapy had an effect on implant exposure. There was an increased rate of exposure in the chemotherapy group, although this did not achieve statistical significance (P = 0.058), but a detrimental effect could not be excluded.

Adolescent↗
PubMed2000

Phacoemulsification time and power requirements in phaco chop and divide and conquer nucleofractis techniques.

PURPOSE: To evaluate the differences in phaco time and power required between the divide and conquer and phaco chop nucleofractis techniques. SETTING: Department of Ophthalmology, Central Middlesex Hospital, London, United Kingdom. METHODS: A retrospective pilot study of 125 patients was followed by a prospective randomized study of 117 patients comparing the phaco chop with divide and conquer techniques in terms of phaco time (minutes), phaco power (%), equivalent phaco time (calculated time required if 100% power had been used throughout), intraoperative and postoperative complications, and postoperative visual acuity. RESULTS: In the pilot study, mean phaco time in the phaco chop group was 1.4 minutes +/- 0.09 (SD) and in the divide and conquer group, 3.4 +/- 0.1 minutes (P <.0001). Mean equivalent phaco time was also less in the phaco chop group (0.39 +/- 0.03 minutes) than in the divide and conquer group (0.98 +/- 0.08 minutes) (P <.0001). In the prospective study, phaco chop required significantly less phaco time (1.2 +/- 0.1 minutes) than divide and conquer (2.4 +/- 0. 1 minutes) (P <.0001), less phaco power (25.3% +/- 1.2% versus 35.1% +/- 1.2%) (P <.0001), and less equivalent phaco time (0.29 +/- 0.02 minutes versus 0.84 +/- 0.05 minutes) (P <.0001). The operating time was shorter in the phaco chop group. There were no differences in complications and postoperative visual acuity. CONCLUSION: This study showed a significant advantage of the phaco chop over the divide and conquer technique in phaco power and duration. Phaco chop also required less operative time and intraocular manipulation without an apparent increase in intraoperative or postoperative complications.

Aged↗
PubMed2000

Incidence, risk factors and outcome of varicella-zoster virus infection in children after haematopoietic stem cell transplantation.

We report a retrospective analysis of VZV infection after haematopoietic stem cell transplantation (HSCT) in children. Thirty-three (30%) of the total 109 children who were transplanted during a 7 year period developed post-transplant VZV infection. Twenty-four of these 33 (73%) children had VZV infection within 1 year following HSCT. The cumulative incidences of post-transplant VZV infection at 1 and 5 years were 26% and 45%, respectively. The positive and negative predictive values of pretransplant VZV serology in recipients on the development of HZ following HSCT were 39% and 88%, respectively. Pretransplant VZV seropositivity in recipients was the only risk factor for post-transplant herpes zoster (HZ) infection on multivariate analysis. All patients responded to acyclovir. The median duration of VZV infection was 5 days. Three (11%) and one (3%) children with HZ developed visceral dissemination and post-herpetic neuralgia, respectively. No mortality was directly attributed to VZV infection. VZV infection remains a major cause of morbidity in children after HSCT. Further studies are warranted to evaluate the potential use of VZV vaccine in these children. Bone Marrow Transplantation (2000) 25, 167-172.

Acyclovir↗
PubMed2000

Early iron reduction programme for thalassaemia patients after bone marrow transplantation.

Thirty thalassaemia patients received iron reduction starting at around 3 months post transplant. Sixteen received desferrioxamine and nine had phlebotomy, five patients had desferrioxamine followed by phlebotomy. The desferrioxamine group had higher serum ferritin levels at the start of iron reduction as compared to the phlebotomy group (5292 vs 2453 microg/l, P EQ 0.001). After 444 and 407 days of iron reduction, serum ferritins at cessation of iron reduction in both groups was similar (665 vs 588 microg/l). The rate of decline of serum ferritin in both groups was similar. There was no graft rejection during the programme. Early institution of iron reduction in ex-thalassaemia is safe.

Adolescent↗
PubMed2000

Single vs twice daily G-CSF dose for peripheral blood stem cells harvest in normal donors and children with non-malignant diseases.

The optimal dose and schedule of G-CSF for mobilization of peripheral blood stem cells (PBSC) is not well defined. G-CSF mobilization was performed in a group of healthy donors and paediatric patients for autologous back-up before receiving allogeneic stem cell transplant. Seventeen consecutive subjects who received G-CSF at 5 microg/kg/dose twice daily (group A) were compared with a historical control group of 25 subjects who received a single daily dose of 10 microg/kg/day G-CSF (group B). Double blood volume apheresis for PBSC collection was started on day 5. G-CSF was continued and apheresis repeated until the targeted CD34+ cell dose was achieved. Both groups were comparable for sex, age, body weight and reason for PBSC collection. Over two-thirds of the subjects in both groups were less than 16 years of age. The G-CSF priming and apheresis were well tolerated. When the first day apheresis products were analyzed, group A resulted in significantly higher yield of total nucleated cells (5.91 vs 3.92 x 108/kg, P = 0. 013), mononuclear cells (5.73 vs 3.92 x 108/kg, P = 0.017), CD34+ cells (2.80 vs 1.69 x 106/kg, P = 0.049) and colony-forming units (107 vs 54 x 104/kg, P = 0.010) as compared with group B. We conclude that the two dose schedule is more efficient in mobilizing PBSC in normal donors and children with non-malignant diseases. This approach may reduce the number of aphereses required and thus reduce the transplant cost.

Adolescent↗
PubMed2000

Umbilical cord blood transplantation for Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI).

Severe Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) is usually fatal by early adulthood. Bone marrow transplantation is the only form of definitive enzyme replacement therapy available. A 5-year-old boy with Maroteaux-Lamy syndrome has successful recovery of bone marrow and enzymatic functions after umbilical cord blood transplant from his unaffected HLA-identical brother. Busulphan (16 mg/kg) and cyclophosphamide (200 mg/kg) were used as preparative chemotherapy with short methotrexate and long cyclosporin as prophylaxis against graft-versus-host disease (GVHD). A total of 6.08 x 10(7)/kg nucleated cells and 2.92 x 10(5)/kg CD34+ cells were transplanted with neutrophil engraftment achieved on day 26. There was no evidence of acute and chronic GVHD. Fifteen months after transplant, a normal level of N-acetylgalactosamine-4-sulphatase activity was achieved despite mixed chimerism. There was clinical improvement of hepatosplenomegaly, facial and skin features, joint mobility and resolution of suppurative middle ear effusion. He returned to school and continued to perform well in academic studies. We report here the first successful umbilical cord blood transplant as treatment of Maroteaux-Lamy syndrome.

Adult↗
PubMed2000

Structural determinants for activation and block of CFTR-mediated chloride currents by apigenin.

Apigenin (4',5,7-trihydroxyflavone) is an activator of cystic fibrosis transmembrane conductance regulator (CFTR)-mediated Cl(-) currents across epithelia at low concentrations and a blocker at high concentrations. We determined the roles of structural components of apigenin for both stimulation and block of Cl(-) currents across Calu-3 epithelia. The half-maximal binding affinity of apigenin for current stimulation (K(s)) was 9.1 +/- 1.3 microM, and the rank-order of molecular structures was 7-hydroxyl > pyrone = 4'-hydroxyl > 5-hydroxyl. Both the 7-hydroxyl and the 4'-hydroxyl served as H-bond acceptors, whereas the 5-hydroxyl was an H-bond donor. The half-maximal binding affinity of apigenin during current block was 74 +/- 11 microM. Blocked Cl(-) currents were structurally determined by 7-hydroxyl = 4'-hydroxyl > pyrone > 5-hydroxyl. Prestimulation of tissues with forskolin significantly affected activation kinetics and binding characteristics. After forskolin stimulation, K(s) was 4.1 +/- 0.9 microM, which was structurally determined by pyrone > all hydroxyls > single hydroxyls. In contrast, block of Cl(-) current by apigenin was not affected by forskolin stimulation. We conclude that apigenin binds to a stimulatory and an inhibitory binding site, which are distinguished by their affinities and the molecular interactions during binding.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2000

Epidermal growth factor induces cell cycle arrest and apoptosis of squamous carcinoma cells through reduction of cell adhesion.

Most squamous epithelial cells are strictly anchorage-dependent cell types. We observed that epidermal growth factor (EGF) promoted the growth of A431 squamous carcinoma cells in suspension cultures but suppressed cell growth and induced apoptosis in monolayer cultures, suggesting that loss of adhesion is responsible for the effects observed in monolayer culture, before cell death. Consistent with this finding, we demonstrated that EGF reduced cell attachment, cell-cell interaction, and cell spreading. Treatment with EGF increased cell adhesion-regulated expression of p21 but suppressed expressions of cyclin A, D1, cdk2, and retinoblastoma protein (pRb), leading to cell cycle arrest and adhesion-regulated programmed cell death. To test directly whether promoting cell adhesion could reduce the effects of EGF, we grew cultures on plates coated with type II collagen. On these plates, cell adhesion was enhanced and EGF treatment had little effect on cell adhesion and apoptosis when cells were attached to the collagen. The collagen effects were dose dependent, and cell cycle and cell cycle-associated proteins were altered accordingly. Finally, when cultures were plated on bacterial Petri dishes, which completely disrupted cell attachment to substratum, the level of apoptosis was greatly higher and cell cycle was arrested as compared with monolayer cultures. Taken together, our results strongly suggest that the EGF-induced cell cycle arrest and apoptosis in monolayer cultures was the result of a decline in cell adhesion.

Apoptosis↗
PubMed1999

Microhook capsule stabilization for phacoemulsification in eyes with pseudoexfoliation-syndrome-induced lens instability.

Cataract extraction in eyes with pseudoexfoliation syndrome is known to result in a high incidence of intraoperative and postoperative complications. Lens instability--phacodonesis--is often present and may lead to zonular rupture, capsule tears, and vitreous loss. We describe the use of microhook iris retractors to stretch and fixate the capsulorhexis relative to the sclera, which stabilizes the capsular bag and facilitates safe phacoemulsification in eyes with pseudoexfoliation-syndrome-induced lens instability. Results of this technique in 8 eyes are reported.

Cataract↗
PubMed1999

beta-Integrin-collagen interaction reduces chondrocyte apoptosis.

We have observed that the spent culture media in suspended chondrocyte cultures is essential for the survival of the cells, since complete change of the spent media induces severe programmed cell death (apoptosis). Moreover, we showed that extracellular matrix (ECM) molecules in the culture media provide vital chondrocyte-matrix interactions; when media are changed, cells are deprived of matrix molecules and undergo apoptosis. In this paper we report that interaction with collagen, a ubiquitous extracellular matrix molecule, is essential for chondrocyte survival. Such an interaction causes chondrocyte aggregation and reduces the level of chondrocyte apoptosis. Hyaluronan, an abundant ECM molecule, can influence the effects of collagen by preventing chondrocyte aggregation. Degradation of hyaluronan with hyaluronidase results in chondrocyte aggregation, and this reduces the level of chondrocyte apoptosis. Experiments with an antibody to integrin beta1 suggest that the collagen-chondrocyte interactions are mediated through integrin beta1, and these interactions may protect chondrocytes from apoptosis. We hypothesize that hyaluronan binds aggrecan and link protein, forming stable ternary complexes, which interact with the chondrocyte surface, perhaps via CD44, and thus maintains a stable chondrocyte-matrix network.

Animals↗