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Biomedical subjects

K Hanna

Publications and source records attributed to K Hanna.

At least 19 recordsLinked to original sources
PubMed2001

Reduction in corneal haze and apoptosis by amniotic membrane matrix in excimer laser photoablation in rabbits.

PURPOSE: To determine whether preserved human amniotic membrane can reduce corneal haze and keratocyte apoptosis induced by excimer laser photoablation in rabbit corneas. METHODS: Excimer photoablation was performed bilaterally in 30 rabbits with a 6.0 mm ablation zone and 120 microm depth using the VISX Star laser with the phototherapeutic keratectomy (PTK) mode. One eye was randomly covered by preserved human amniotic membrane secured with 4 interrupted 10-0 nylon sutures, and the other eye served as the control. The amniotic membranes were removed at 1 week, and corneal haze was graded with slitlamp biomicroscopy by 3 masked corneal specialists biweekly for the ensuing 12 weeks until the rabbits were killed. Another 18 rabbits were divided into 4 subgroups and received PTK alone, PTK with membrane, PTK with sham sutures, or PTK with tarsorrhaphy. All eyes were studied histologically, and 3 eyes in each group were studied by in situ terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling assay at 1, 3, and 7 days and 12 weeks, respectively. RESULTS: A consistent grading of differences in corneal haze scoring between the control corneas and the amniotic-membrane-covered corneas was noted among the 3 masked observers. Organized reticular post-PTK corneal haze peaked at 7 weeks in both groups, and the corneal haze score in the amniotic-membrane-covered group was significantly less than in the control group from 7 to 12 weeks (all P < .001). Compared to the control corneas, the amniotic-membrane-covered corneas had less inflammatory response at 1 and 3 days, less keratocyte apoptosis in the ablated anterior corneal stroma at 1, 3, and 7 days (P < .001), and less stromal fibroblast cellularity and epithelial hyperplasia at 12 weeks. CONCLUSIONS: Amniotic membrane matrix introduced at an early stage of the corneal wound healing process effectively reduced corneal haze induced by excimer laser photoablation in rabbits. Studies linking suppression of apoptosis in the acute wound-healing process with reduction of subsequent corneal scarring may have useful clinical applications.

Amnion↗
PubMed2000

Predictive factors associated with axillary lymph node metastases in T1a and T1b breast carcinomas: analysis in more than 900 patients.

BACKGROUND: Axillary lymph node metastasis (ALNM) represents the single most important prognostic indicator in patients diagnosed with breast cancer. The proportion of < or = 1-cm (T1a, T1b) invasive breast carcinomas is increasing. The incidence and predictive factors associated with ALNM in patients with < or = 1-cm tumors remains unclear and the role of axillary lymph node dissection in these patients has been questioned. The purpose of this study was to determine clinical and pathologic factors predictive of ALNM in patients with < or = 1-cm invasive breast carcinomas by univariate and multivariate analyses. STUDY DESIGN: Review analysis from a prospective database identified patients with < or = 1-cm invasive breast cancers treated at our institution between 1990 and 1996. All patients underwent a resection of the primary tumor and axillary lymph node dissections. Routine patient and tumor characteristics evaluated included: age, race, tumor size, histologic grade, estrogen and progesterone receptor status, and lymphatic and vascular invasion. Univariate and multivariate analyses were performed. Adjusted odds ratios (OR) and 95% confidence intervals (CI) are presented. RESULTS: A total of 919 patients were identified in this study with tumors < or = 1 cm. These included 199 patients (21.7%) with T1a tumors and 720 patients (78.3%) with T1b tumors. ALNM was detected in 165 patients with an overall incidence of 18.0%. Of the ALNM group, 32 patients (19.4%) had T1a tumors and 133 patients (80.6%) had T1b tumors. Four variables were found to be significant in univariate analysis. These included: increasing tumor size, poor histologic grade, presence of lymphatic or vascular invasion, and younger age of the patient. An increase in tumor size was associated with a significant risk of ALNM (OR = 2.66, 95% CI = 1.28 to 5.75; p = 0.01). Poor tumor grade and the presence of lymphatic or vascular invasion were also associated with an increased risk of ALNM (OR = 2.69, p = 0.003 and OR = 5.52, p = 0.0001, respectively). Patients with ALNM were more likely to have a tumor grade of 3 (25.0% ALNM versus 12.5% node-negative, p = 0.004) and lymphatic or vascular invasion (16.9% ALNM versus 3.5% node-negative, p < 0.0001). In multivariate analysis, an increased risk of ALNM was demonstrated with increasing tumor size (0.1-cm increments), poor histologic grade, and younger age. CONCLUSIONS: This study investigated clinical and pathologic factors influencing ALNM in patients with T1a and T1b breast carcinomas. We have identified three factors by multivariate analysis as significant independent predictors of ALNM in this group of patients. These include increasing tumor size, poor histologic grade, and younger age. Given the significant amount of ALNM demonstrated in this study (overall 18%) and the inability to identify a subgroup of patients that had an acceptable low risk of ALNM, the complete omission of assessing the axilla for metastatic disease in patients with small breast cancers cannot be advocated. Our recommendation for patients diagnosed with T1a and T1b tumors is to have their axilla investigated for metastatic disease either by traditional axillary lymph node dissections or by intraoperative lymphatic mapping and sentinel lymph node biopsy techniques.

Adult↗
PubMed2000

Changes in liver function tests after laparoscopic cholecystectomy: not so rare, not always ominous.

The incidental findings of increased alanine aminotransferase (ALT) and aspartate amino transferase (AST) after uneventful laparoscopic cholecystectomy (LC) prompted us to investigate the incidence and the clinical significance of this phenomenon. Changes in liver function test after LC (n = 55) were compared with those after OC (n = 16). Liver function tests were obtained preoperatively and postoperatively on days 1, 2, and 7. All of the patients fulfilled the selection criteria: normal preoperative liver function test and no endoscopic retrograde cholangiopancreatography, common bile duct exploration, or postoperative biliary complications (injury, infection, or obstruction). Converted cholecystectomies were also excluded. During LC, the intra-abdominal pressure was maintained within the conventional range of 14 to 15 mm Hg. ALT had doubled in the first 48 hours from the preoperative mean in 58.2 per cent in LC patients versus only 6.3 per cent in the OC group. AST doubled from the preoperative mean value in 38.2 per cent in the LC group versus only 6.3 per cent in the OC group. By the 7th postoperative day, the enzymes returned to the preoperative values in both the LC and the OC group. In many instances, a significant increase in ALT and AST blood levels occurred after uneventful LC. The phenomenon is transient as these enzymes returned to normal value within 7 days. These changes are clinically silent in patients with a normal liver function.

Adult↗
PubMed1999

Efficacy and safety of cerivastatin in primary hypercholesterolemia: a long term comparative titration study with simvastatin.

OBJECTIVE: To compare cerivastatin with simvastatin in their long term safety and efficacy in reducing low density lipoprotein cholesterol (LDL-C). DESIGN: Multicentre, randomized, double-blind, parallel group study. SETTING: Thirteen Canadian centres. PATIENTS AND METHODS: A total of 387 patients with primary hypercholesterolemia received treatment with either cerivastatin (0. 05 to 0.3 mg/day) or simvastatin (5 to 40 mg/day) to achieve plasma LDL-C levels below 3.36 mmol/L (130 mg/dL) for an initial 32-week dose-titration phase and a subsequent 72-week extension phase. MAIN RESULTS: Cerivastatin and simvastatin produced clinically significant reductions in LDL-C of 28.4% and 35.4%, respectively, at the end point for the 32-week study, and reductions of 32.8% and 35. 0%, respectively, at the end of the extension phase of the study. Response rates (a greater than 15% drop in LDL-C) were comparable for the two treatments (88.9% cerivastatin versus 93.2% simvastatin) at the 32-week end point. Response rates were 100% for both treatments at the end of the 72-week extension phase. Both treatments also reduced total cholesterol, apolipoprotein B and very low density lipoprotein cholesterol levels. Cerivastatin and simvastatin increased HDL-C levels significantly by 8.8% and 11.0%, respectively, at the end point for the 32-week study, and by 8.6% and 12.1%, respectively, at the end of the extension phase of the study. Treatments were well tolerated, and the incidence of adverse effects was similar in both groups. CONCLUSIONS: This forced titration study demonstrates that cerivastatin, given once daily at doses up to 0.3 mg/day, is effective and well tolerated. The results of this study support further investigation of higher doses of cerivastatin given the excellent safety profile at doses up to 0.3 mg.

Anticholesteremic Agents↗
PubMed1998

Laparoscopic appendectomy in children.

Laparoscopic appendectomy is a common surgery in most pediatric surgical centers. Many studies, mostly retrospective reviews in adults, show the advantages of the laparoscopic approach to be less wound infections, shortened postoperative recovery, and faster return to normal activities. In addition, less analgesic medication is required postoperatively. Potential disadvantages of laparoscopic appendectomy include an increased operative time, elevated costs when disposable instruments are used, and possibly more infectious complications when performed for complicated appendicitis. There are no prospective, randomized trials comparing laparoscopic versus open appendectomy in children. Until these studies are completed, questions will persist regarding the benefits of laparoscopic appendectomy in children.

Adult↗
PubMed1997

Multicultural considerations for the advanced practice nurse anesthetist in the preoperative teaching area.

This article investigates the effects of multiculturism and diversity on the ability of the preoperative certified registered nurse anesthetist (CRNA) educator to convey effective information to the culturally diverse surgical patient. It looks at the importance of preoperative instruction across all populations in relation to hospital length of stay, need for postoperative pain medication, ambulation, and postoperative urinary retention. The article extrapolates these data to the culturally diverse population and gives a concrete plan of care for the advanced practice CRNA to modify teaching methods to facilitate the teaching-learning encounter in the culturally diverse population.

Community Health Planning↗
PubMed1992

[Use of perfluorocarbon solutions in the surgical treatment of posterior luxation of the lens].

Posterior lens dislocations represent 20 to 40% of all lens dislocations. It can occur after trauma. Visual prognosis can be good, but most often there are complications such as glaucoma, retinal detachment and uveitis. A few years ago, surgery was difficult, and surgery was delayed until the development of specific complications. A new technique, using perfluorocarbon liquids (PFCL), should be recommended because it is simple, and constantly effective. After vitrectomy, perfluorodecalin is injected into the vitreous cavity. As PFCL have a density twice the density of water, it allows the lens to float on the surface of the PFCL, behind the iris. Lens extraction can be associated with trabeculectomy, and anterior chamber lens implantation. We present a prospective study of 6 cases operated according to this technique. Postoperative results were good: visual acuity was preserved and ocular tension was controlled in cases of preoperative hypertonia. We believe this technique can be recommended after posterior lens dislocation, to prevent complications and to preserve visual acuity.

Aged↗
PubMed1990

Healing of excimer laser ablated monkey corneas. An immunohistochemical evaluation.

The healing response of the cornea following excimer laser anterior keratomileusis (a 4-mm-diameter ablation to a depth of 11, 23, or 46 microns) was analyzed immunohistochemically in adult rhesus monkeys. The ablated surface had reepithelialized and the synthesis of type VII collagen (a major component of anchoring fibrils) was evident by 7 days; the reestablishment of a nearly continuous anchoring fibril zone was evident after 12 weeks. Stromal fibroblasts, activated in response to wounding, expressed a fetal antigen for approximately 6 weeks. Although fibronectin and type VII collagen were present only transiently in the regenerating subepithelial stromal matrix in the subepithelial regions, some other alterations, including the presence of type III collagen, increased levels of keratan sulfates, and discontinuities in the anchoring fibril zone were evident even 18 months after wounding. The depths of the regenerated stroma, which were estimated from the depths of remnant staining for type VII collagen in the stromal matrix, generally, but not always, corresponded to the depths of the calculated ablation.

Animals↗
PubMed1990

Music during learning of a tactual-spatial task affects later response generalization.

Equal numbers of men and women learned a finger maze, with half of the subjects initially using their right hands and the other half using their left hands. To reach criterion, subjects receiving music in the ear ipsilateral to the hand used required more trials than did those receiving no music. Furthermore, when the right hand ran the maze, music played to the ipsilateral ear also delayed learning, compared with music played contralaterally. Binaural music delayed learning when the left hand was used but not when the right hand was used. Possible causes of these effects are suggested. When subjects switched hands and relearned the maze, the number of trials to criterion depended on the group subjects were in during initial learning and not on the group they were in during the hand reversal (response generalization) trials. Although the music condition used determined the effect of music on initial learning and on response generalization, some evidence is presented that indicates that the two effects are not entirely interdependent and that they may even involve different mechanisms.

Adult↗
PubMed1990

[Is there a future for the Excimer laser in refractive surgery?].

The refractive surgery concerns all the surgical procedures implicated in the refractive power change of the cornea. Its clinical results are just known, and a new physical procedure is becoming capable to replace surgery: the Excimer laser. Without any instrumental contact with the corneal surface, the laser beam is able to remodel the corneal tissue, and to treat astigmatism, myopia, hypermetropia. Millions of people could be treated by such a laser, and could leave their glasses. Biological effects on rabbit and monkeys are presented. An argon fluoride excimer laser (193 nm) with a moving slit delivery system was used to perform anterior myopic keratomileusis in both eyes of 37 rabbits and 15 monkeys. Histological analysis of the corneas was made after ablation and at intervals up to 20 months. By slit examination at the longer follow up time, 60% of treated rabbits and 40% of treated monkeys keep a clear cornea, but the others had central spotty subepithelial haze. Light and electron microscopy documented corneal healing. In the clear corneas a good reconstitution of the epithelium, its basal lamina was observed, and anterior stromal corneas contained few active fibrocytes with a good preservation of the connective lamellar structure. On the contrary, in the cornea with opacification focal areas of 20 microns thick subepithelial scarring were present and the interface between epithelial cells and anterior stroma remained disturbed by incomplete, disrupted or duplicated basal lamina. Differences between the responses of monkeys, rabbits corneas to the same photoablation procedure remain unclear.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Potential use of lasers for penetrating keratoplasty.

Experimental corneal trephination has been achieved with the 193 nm argon fluoride excimer and 2.9 microns hydrogen fluoride and Er:YAG laser systems. Compared with metal blades and other lasers, the 193 nm excimer laser creates the best quality corneal excision, but has a relatively slow etch rate through the stroma, and its use requires toxic gas. The mid-infrared laser systems trephine the cornea in less than 10 seconds, but cause a 10 microns to 15 microns zone of adjacent stromal damage and create wounds that are approximately 2.5 times larger than wounds made by metal scalpels. The wavelength and laser pulse duration influence the cutting characteristics of the laser. Optical delivery systems using an axicon lens, a rotating slit, and a computer controlled scanning optical system have been developed for penetrating keratoplasty. Selection of the optimal laser system for penetrating keratoplasty must await further experimental studies. Refinements of the laser cavity and delivery system are necessary before clinical studies can begin. A carefully controlled randomized clinical trial comparing laser trephination with conventional mechanical trephines will be necessary to determine the safety and efficacy of a laser trephination system.

Cornea↗