Cement migration after THR. A comparison of charnley elite and exeter femoral stems using RSA

Studies using roentgen stereophotogrammetric analysis (RSA) have shown that the femoral components of cemented total hip replacements (THR) migrate distally relative to the bone, but it is not clear whether this occurs at the cement-implant or the cement-bone interface or within the cement mantle. Our aim was to determine where this migration occurred, since this has important implications for the way in which implants function and fail. Using RSA we compared for two years the migration of the tip of the stem with that of the cement restrictor for two different designs of THR, the Exeter and Charnley Elite. We have assumed that if the cement restrictor migrates, then at least part of the cement mantle also migrates. Our results have shown that the Exeter migrates distally three times faster than the Charnley Elite and at different interfaces. With the Exeter migration was at the cement-implant interface whereas with the Charnley Elite there was migration at both the cement-bone and the cement-implant interfaces.     

Iris crystals in chronic uveitis.

AIMS: To analyse the unusual physical sign of iris crystals occurring in patients with uveitis. METHODS: Demographic details and clinical features were documented in 24 patients with chronic uveitis and iris crystals. Plasma immunoglobulin subclasses were measured, and a histopathological review of iridectomy specimens from 33 patients with chronic uveitis was also undertaken. RESULTS: The mean age of patients was 38 years, with a slight preponderance of females. 17 patients had Fuchs' heterochromic cyclitis although a number of other uveitis entities were represented. There was no correlation between severity of clinical signs and presence of iris crystals. Over a mean follow up period of 15 months no significant change in the number, size, or position of the crystals was seen except in four patients who underwent intraocular surgery. Only three patients had raised plasma IgG1. The review of the histology of iridectomy specimens failed to show evidence of Russell body formation in any patient. CONCLUSIONS: Iris crystals appear to be rare but may be underreported as they are small and can easily be missed. They are likely to be associated with disease processes in which there is active immunoglobulin production within the anterior chamber, such as Fuchs' heterochromic cyclitis.     

Pretranslational up-regulation of the hepatic microsomal delta4-3-oxosteroid 5alpha-oxidoreductase in male rat liver by all-trans-retinoic acid.

Administration of all-trans-retinoic acid (ATRA; 60 mg/kg daily for 3 days) to male rats increased the rate of 5alpha-dihydrotestosterone (5alpha-DHT) formation from testosterone in microsomal fractions in vitro. The formation of androstane-3alpha,17beta-diol from testosterone was also increased because of the higher concentration of 5alpha-DHT produced in microsomal incubations. Northern analysis confirmed that the increased rate of 5alpha-DHT formation was due to the pretranslational up-regulation in delta4-3-oxosteroid 5alpha-oxidoreductase (EC 1.3.99.5) mRNA expression in ATRA-treated male rat liver. Thus, ATRA elicited in male rat liver a partial feminization of the expression of this enzyme, which normally exhibits a female-selective distribution in the rat. Subsequent experiments evaluated whether the administration of human chorionic gonadotropin or thyroxine to ATRA-treated male rats decreases 5alpha-reductase activity to that observed in untreated male rat liver. Although these treatments did not decrease 5alpha-reductase to untreated male levels, it was found that administration of ATRA to gonadectomized male rats produced complete feminization of the enzyme. Again, up-regulation was confirmed at the mRNA level. The activity of the male-specific cytochrome P450 2C11 (as reflected by microsomal testosterone 16alpha-hydroxylation activity) was correspondingly decreased by treatments that increased steroid 5alpha-reductase activity. Thus, gonadectomy in combination with ATRA administration effected a more pronounced decrease in 16alpha-hydroxylation activity than either treatment alone. These findings suggest that ATRA is a novel positive regulator of the 5alpha-reductase that in combination with the removal of circulating androgen, which normally suppresses 5alpha-reductase levels, feminizes the expression of this enzyme in rat liver.     

A comparative study in rats of the in vitro and in vivo pharmacology of the acetylcholinesterase inhibitors tacrine, donepezil and NXX-066

The in vitro and in vivo effects of the novel acetylcholinesterase inhibitors donepezil and NXX-066 have been compared to tacrine. Using purified acetylcholinesterase from electric eel both tacrine and donepezil were shown to be reversible mixed type inhibitors, binding to a similar site on the enzyme. In contrast, NXX-066 was an irreversible non-competitive inhibitor. All three compounds were potent inhibitors of rat brain acetylcholinesterase (IC50 [nM]; tacrine: 125 +/- 23; NXX-066: 148 +/- 15; donepezil: 33 +/- 12). Tacrine was also a potent butyrylcholinesterase inhibitor. Donepezil and tacrine displaced [3H]pirenzepine binding in rat brain homogenates (IC50 values [microM]; tacrine: 0.7; donepezil: 0.5) but NXX-066 was around 80 times less potent at this M1-muscarinic site. Studies of carbachol stimulated increases in [Ca2+]i in neuroblastoma cells demonstrated that both donepezil and tacrine were M1 antagonists. Ligand binding suggested little activity of likely pharmacological significance with any of the drugs at other neurotransmitter sites. Intraperitoneal administration of the compounds to rats produced dose dependent increases in salivation and tremor (ED50 [micromol/kg]; tacrine: 15, NXX-066: 35, donepezil: 6) with NXX-066 having the most sustained effect on tremor. Following oral administration, NXX-066 had the slowest onset but the greatest duration of action. The relative potency also changed, tacrine having low potency (ED50 [micromol/kg]; tacrine: 200, NXX-066: 30, donepezil: 50). Salivation was severe only in tacrine treated animals. Using in vivo microdialysis in cerebral cortex, both NXX-066 and tacrine were found to produce a marked (at least 30-fold) increase in extracellular acetylcholine which remained elevated for more than 2 h after tacrine and 4 h after NXX-066.     

Intraoperative laparoscopic complications

PURPOSE: The aim of this study was to assess various intraoperative and postoperative complications associated with laparoscopic colorectal surgery. Specifically, the impact of surgical experience and procedure type on complications was analyzed. METHODS: All patients who underwent laparoscopic surgery were analyzed by age, sex, surgical indications, procedure performed, procedure length, intraoperative and postoperative complications, incidence and causes for conversion, duration of postoperative ileus, and length of hospital stay. Patients were classified for type of procedure and chronologically into four consecutive groups. Procedures were also categorized into four different groups: GI, total abdominal colectomies; GII, segmental resections; GIII, diverting procedures; GIV, others (abdominoperineal resection, Hartmann's creation or closure, anterior resection, and rectopexy). RESULTS: Between August 1991 and October 1995, 167 patients of a mean age of 49.6 (15–88) years underwent laparoscopic colorectal procedures. All procedures were electively performed. Common indications for surgery included inflammatory disease in 70 (42 percent), neoplasia in 56 (33 percent), functional bowel disorders in 30 (18 percent), and other forms of colorectal disorders in 11 (7 percent) patients. The most significant variable affecting intraoperative laparoscopic complication rate was surgical experience measured as the time interval during which surgery was performed (P=0.02). Total complication rate decreased from 29 percent during the first period to 11 percent by the second period (P<0.04) and 7 percent during the third period (P<0.005). Thus, the learning curve appeared to have required more than 50 cases to achieve. Moreover, even after performance of 94 (1991–1993) procedures in GI and GIV, these procedures were associated with higher complication rates than were those procedures in GII and GIII (P=0.04). CONCLUSION: Surgical experience and case selection are the most critical variables by which the surgeon can decrease the intraoperative laparoscopic complication rate.     

Prospective comparison of open<Emphasis Type="Italic">vs</Emphasis>. laparoscopic colon surgery for carcinoma

Laparoscopy for colonic diseases began in 1990 and has established a role in benign disease. Early observations and experiences demonstrated feasibility of laparoscopic surgery for a variety of colonic disease processes, but the applicability to colonic carcinoma was unclear. METHODS: In 1990, we began a comparative study of open (OCR)vs.laparoscopic (LCR) approach to colon cancer. The study progressed 65 months, with 224 patients in OCR group and 191 patients in LCR group. Parameters studied are stage, location, length of specimen, number of lymph nodes resected, margins, postoperative course, wound complications, recurrence rates, and immediate and long-term survival. OCR were standardized by one group, and LCR were standardized by a second group. All patients undergoing LCR were given freedom to choose either OCR or LCR, and informed consent was obtained. RESULTS: Equal or greater lymph node retrieval, resections, and distal margins were evident with LCR. Benefits with LCR were shown with shorter hospitalization (5.7vs.9.7 days), less blood loss, less wound problems (1vs.14), and quicker return of bowel function. Survival, recurrence, and death rates were essentially the same. There were no trocar implants in the LCR group. CONCLUSION: After five years, this study shows that laparoscopy does no harm to the patient, offers comparable oncologic resections, and seems to be patient-friendly, with less pain, quicker return of bowel functions, shortened hospitalization, and quicker return to full activity.     

Strategies in the treatment of diffuse pontine gliomas: the therapeutic role of hyperfractionated radiotherapy and chemotherapy

This article will review the current treatment of pediatric patients with diffuse pontine gliomas (DPG) and discuss three potential avenues of therapeutic research including (i) radiotherapy (RT) in combination with radiation sensitizers, (ii) dose-intensive, induction chemotherapy with hematopoietic support followed in sequence with RT applied as a consolidation therapy, and (iii) the interleafed application of phase-specific chemotherapeutic agents and hyperfractionated external beam radiotherapy (HFEBRT) referred to as chemoradiotherapy.