Osteonecrosis of the Femoral Head: Etiology, Investigations, and Management.

Femoral head osteonecrosis is a condition caused by a compromise of the blood supply of the femoral head. The precarious blood supply of the head and its role as a major weight-bearing joint makes it one of the most common bones to be affected by osteonecrosis. We describe the etiology, clinical presentation, investigations and common management options used nowadays to treat it.

Risk factors involved in spread of HCV in patients from sub urban Rawalpindi and their association with existing genotypes.

The current epidemiological study was designed to trace the involved risk factors in Hepatitis C Virus (HCV) spread and to identify any association between HCV genotypes and risk factors. Blood samples were taken from 400 participants and viral genotyping was performed in order to find any possible relationship between the risk factors and genotypes. Major genotypes included 3, 1, 4 and several untypeable ones with prevalence rates 65%, 22.5%, 2.75% and 9.75% respectively. Surgery and dental procedure were strongly related to the spread of genotype 3b, while genotype 1b was strongly related to blood transfusion and dental procedures as a single combination risk factor. On the other hand genotypes 1a, 3a, 4 and the untypeable genotypes, were equally affected by all reported risk factors. The probability of occurrence of genotype 3a with reference to dental procedures was 11%. Dental procedures, unsafe injection and surgical procedures are the main risk factors while the blood transfusion in combination with dental procedures has emerged as a potent risk factor in the transmission of HCV.

Hydrogen induced optically-active defects in silicon photonic nanocavities.

We demonstrate intense room temperature photoluminescence (PL) from optically active hydrogen- related defects incorporated into crystalline silicon. Hydrogen was incorporated into the device layer of a silicon on insulator (SOI) wafer by two methods: hydrogen plasma treatment and ion implantation. The room temperature PL spectra show two broad PL bands centered at 1300 and 1500 nm wavelengths: the first one relates to implanted defects while the other band mainly relates to the plasma treatment. Structural characterization reveals the presence of nanometric platelets and bubbles and we attribute different features of the emission spectrum to the presence of these different kind of defects. The emission is further enhanced by introducing defects into photonic crystal (PhC) nanocavities. Transmission electron microscopy analyses revealed that the isotropicity of plasma treatment causes the formation of a higher defects density around the whole cavity compared to the ion implantation technique, while ion implantation creates a lower density of defects embedded in the Si layer, resulting in a higher PL enhancement. These results further increase the understanding of the nature of optically active hydrogen defects and their relation with the observed photoluminescence, which will ultimately lead to the development of intense and tunable crystalline silicon light sources at room temperature.

Some challenges to progressive control of foot and mouth disease in Pakistan--findings of a pilot survey.

Pakistan is at an initial stage for progressive control of foot and mouth disease (FMD). Understanding the risk factors for introduction, spread and persistence of the infection is important to design an evidence-based disease control programme. A rapid appraisal method was adopted, and a convenient sample of twenty commercial dairy farmers was interviewed. The following were considered to contribute in secondary transmission of infection: (i) intermediaries and service providers [animal health workers, animal traders and transporters, raw milk collectors, persons who remove skin of dead animals], (ii) places where animals come in close contact [livestock markets, animal fairs, communal grazing pastures, routes in villages where livestock move, watering points, animal transport vehicles], (iii) use of bulls immediately after recovery from FMD infection, (iv) range land/desert livestock production, (v) small holder sheep and goat production, (vi) purchase of replacement stock and fodder from infected locations. This article reveals contacts within and between villages, some of which may act as routes of transmission of FMD. The study suggests the need for zoosanitary education of the livestock keepers.

Enhanced 1.54 µm emission in Y-Er disilicate thin films on silicon photonic crystal cavities.

We introduce an Y-Er disilicate thin film deposited on top of a silicon photonic crystal cavity as a gain medium for active silicon photonic devices. Using photoluminescence analysis, we demonstrate that Er luminescence at 1.54 µm is enhanced by coupling with the cavity modes, and that the directionality of the Er optical emission can be controlled through far-field optimization of the cavity. We determine the maximum excitation power that can be coupled into the cavity to be 12 mW, which is limited by free carrier absorption and thermal heating. At maximum excitation, we observe that nearly 30% of the Er population is in the excited state, as estimated from the direct measurement of the emitted power. Finally, using time-resolved photoluminescence measurements, we determine a value of 2.3 for the Purcell factor of the system at room temperature. These results indicate that overcoating a silicon photonic nanostructure with an Er-rich dielectric layer is a promising method for achieving light emission at 1.54 µm wavelength on a silicon platform.

Interobserver and intraobserver reliability and validity of the Vancouver classification system of periprosthetic femoral fractures after hip arthroplasty.

The Vancouver classification system of periprosthetic fractures has been revalidated in this study, using the radiographs of 45 patients. Three consultants and 3 trainees reviewed the radiographs independently, on 2 separate occasions, at least 2 weeks apart. Interobserver and intraobserver agreement and validity were analyzed, using weighted κ statistics. The mean κ value for interobserver agreement was found to be 0.69 (0.63-0.72) for consultants and 0.61 (0.56-0.65) for the trainees, both representing substantial agreement. Intraobserver κ values ranged from 0.74 to 0.90, showing substantial agreement. Validity analysis of 37 type B cases revealed 81% agreement within B1, B2, and B3 subgroups with a κ value of 0.68 (substantial agreement). This study has reconfirmed the reliability and validity of the Vancouver classification while it also emphasizes the intraoperative assessment of implant stability.

Chorioretinal vascular oxygen tension in spontaneously breathing anesthetized rats.

PURPOSE: To establish baseline and variability of oxygen tension (PO(2)) measurements in the choroid, retinal arteries, capillaries, and veins of spontaneously breathing anesthetized rats and determine the effect of a moderate surgical procedure on the chorioretinal PO(2). METHODS: Our previously established optical section phosphorescence imaging technique was utilized to measure PO(2) in the chorioretinal vasculatures. Imaging was performed in 29 spontaneously breathing rats under ketamine/xylazine anesthesia. In 7 rats, blood was drawn using a surgically implanted femoral arterial catheter and analyzed to determine the systemic arterial PO(2). The PO(2) measurements in 22 rats without surgery (group 1) and 7 surgically instrumented rats (group 2) were statistically compared. The intrasubject variability was calculated by the average standard deviation (SD) of repeated measurements. RESULTS: The average systemic arterial PO(2) was 52 +/- 7 mm Hg (mean +/- SD) in group 2. In group 1, the average PO(2) measurements in the choroid, retinal arteries, capillaries, and veins were 50 +/- 11, 40 +/- 5, 39 +/- 6, and 30 +/- 5 mm Hg, respectively. No statistically significant PO(2) differences in any of the chorioretinal vasculatures were found between the two groups (p > 0.4). The intrasubject variability was 3 mm Hg in the choroid, retinal arteries, capillaries, and veins. CONCLUSIONS: Chorioretinal PO(2) measurements in spontaneously breathing anesthetized rats have a relatively low variability, indicating that PO(2) changes due to various physiological alterations can be reliably assessed.

Macular thickness mapping in exudative age-related macular degeneration.

PURPOSE: To report the feasibility of retinal thickness mapping for evaluating thickness differences in retinal areas with and without leakage shown by fluorescein angiography for patients who have age-related macular degeneration with choroidal neovascularization. METHODS: A custom-built version of the retinal thickness analyzer was used for thickness mapping. Retinal thickness was defined as the separation between vitreoretinal and pigment epithelium-choroid interfaces. Imaging was performed in 1 eye of 10 patients with the clinical diagnoses of age-related macular degeneration and choroidal neovascularization. Patients either had never undergone photodynamic therapy at the time of measurement (untreated) or had received one or more photodynamic therapy treatments (treated). Average retinal thicknesses in selected areas with and without the presence of leakage shown by fluorescein angiography were calculated and compared statistically. RESULTS: Retinal thickness (mean +/- SD) in areas with leakage (315 +/- 54 microm) was significantly greater than that in areas without leakage (280 +/- 28 microm) (P = 0.03). In untreated patients, areas with leakage (345 +/- 45 microm) were significantly thicker than areas without leakage (289 +/- 23 microm) (P = 0.02). In treated patients, retinal thickness in areas with leakage (271 +/- 33 microm) and without leakage (267 +/- 34 microm) was similar. CONCLUSION: Retinal thickness mapping may prove to be useful as an adjunct to fluorescein angiography to monitor choroidal neovascularization and its treatment.

Influence of aluminium on neurotoxicity of lead in adult male albino rats.

Influence of aluminium on neurotoxicity of lead was studied in male albino rats. Aluminium enhanced the net deposition of lead in brain. This was further substantiated by higher levels of malondialdehyde (MDA), and lower activities of acetylcholinesterase enzyme in the brain homogenates of the rats treated with both lead and aluminium as compared to those of rats treated with lead only. In lead plus aluminium treated animals, a significant neurological deficit was observed when the animals were subjected to rota-rod, traction performance (TP) and tail immersion tests.

A new assembly and technique for testing insecticides.

A new design of insecticide testing assembly has been devised that is highly versatile in testing the efficacy, potency and interaction of insecticides and other test chemicals. The merits of the assembly and technique have been explained.

Beneficial effects of aluminum on the progression of lead-induced nephropathy in rats.

We studied the effect of aluminum on lead-induced nephropathy in male albino rats. Five groups of male albino rats were given either water only or lead acetate (125 mg/kg body weight) and/or aluminum chloride (50 mg/kg body weight or 100 mg/kg body weight) for a period of 90 days. Aluminum was found to prevent the lead-induced increase in the relative organ (kidney) weight in a dose-dependent manner. Aluminum also prevented lead-induced increase in plasma creatinine levels of the treated animals. Estimation of lead concentration in kidneys of different treatment groups revealed that the net deposition of lead was lower in animals which were given both lead acetate and aluminum chloride simultaneously. The results showed that aluminum offers some protection against lead-induced nephrotoxicity in a time- and dose-dependent manner.

New sheath for vascular access and subcutaneous drug administration: multicenter clinical trial for pain prevention after cardiac catheterization.

A new vascular sheath design (anesthesia infusion sleeve, or AIS) was developed to enable administration of local anesthetics or other medications into the subcutaneous tissue around an arterial or venous insertion site without any additional needle sticks or manipulation. Design, animal testing, and an initial small single-site clinical study have previously been published. The current study was multicenter and randomized 80 patients to use of a standard sheath for vascular access or the AIS. Pain associated with sheath placement, postprocedure pain, and pain associated with sheath removal before and during manual compression was recorded. Baseline pain was identical in both the standard and AIS groups. Pain during infiltration and with initial femoral artery compression was significantly lower in the AIS group. A quality of life questionnaire indicated that the AIS sheath was associated with less discomfort and was preferred over a standard sheath in patients who had had a previous procedure performed. The AIS represents a simple addition to standard sheath design, offering superior pain control during removal compared to the standard technique, without the need for systemic analgesics or additional needle punctures.

Studies on end-to-end colonic anastomosis in the dog: a comparison of techniques.

For end-to-end anastomosis, many techniques suitable for the small intestine end up catastrophically when applied on the colon. An experimental study involving 18 healthy adult dogs was conducted to find a model technique out of the best considered techniques for small intestinal end-to-end anastomosis viz., simple interrupted approximating sutures (group I), double-layer inverting sutures (group II), and Gambee sutures (group III). The results depicted a nonsignificant difference among groups as far as paralytic ileus and omental adhesions are concerned. Similarly, haematologic and physiologic values did not deviate from a normal pattern after any surgical intervention. Barium sulphate radiographs taken at postoperation (PO) day 14 revealed significantly lesser reduction (P < or = 0.001) in lumen diameter (26.14 +/- 1.87%) at the site of anastomosis in group I as compared to 30.16 +/- 1.20% and 38.91 +/- 1.87% reduction in groups III and II, respectively. Similarly, gain in tensile strength was maximum (26.55 +/- 1.33%) in group I and minimum (19.73 +/- 2.62%) in group II on PO day 14. The current study showed superiority of the simple interrupted suture technique for colonic end-to-end anastomosis over the other two techniques studied.

Clinical perspectives of intravenous ketamine anaesthesia in peafowl (Pavo cristatus).

A total of 29 peafowl (Pavo cristatus), rectified surgically for infraorbital abscesses (n = 22), lacerated wounds (n = 4), and fractures of tibia (n = 2) and radius (n = 1), were anaesthetized by the intravenous administration of ketamine hydrochloride (Inj. Calypsol, Gedeon Richter, Hungary) in a dose of 15 20 mg/kg body weight. Divided doses (10 mg + 5 mg + 5 mg) were used with an interval of 1-2 min. No premedication was undertaken in any of the birds. Anaesthesia lasted for about 15 min and the birds gained their feet completely after 30 min to 3 hours. The respiration rate was markedly depressed (8-10/min) and the respiratory pattern was deep abdominal. Only a slight increase was observed in the heart rate. Analgesia was incomplete and muscle relaxation was not satisfactory. Mild salivation was also noticed in some of the birds (n = 3). Recovery, although not smooth, was uneventful.

New vascular sheath for subcutaneous drug administration: design, animal testing, and clinical application for pain prevention after angioplasty.

A new vascular sheath design (anesthesia infusion sleeve or AIS) was developed to enable administration of local anesthetics or other medications into the subcutaneous tissue around the insertion site without any additional needle sticks or other manipulation. Design of the system was based upon anatomic measurements of femoral artery depth in 150 patients. Animal studies of prototypes verified subcutaneous delivery using both radiographic methods and direct dissection. The pharmacokinetic profile of plasma lidocaine was also studied in three pigs to document subcutaneous delivery with the AIS. Subsequently a clinical trial of the AIS versus a standard sheath was done in 20 patients undergoing coronary angioplasty. Pain associated with sheath removal was graded using a verbal scale at baseline, during infiltration of the area, and at 1-min intervals during compression for 15 min. Baseline pain was identical in both groups, whereas, during infiltration with lidocaine, pain increased in the standard sheath group and decreased in the AIS group. Pain increased slightly in both groups with initial compression; however, it was significantly less in the AIS group. This difference persisted for several minutes after initial compression. The AIS represents a simple addition to standard sheath protocol offering superior pain control compared to standard technique for sheath removal without the need for systemic analgesics or other medications.

Prevalence of intraatrial thrombus in patients with atrial flutter.

In summary, left atrial thrombus occurs with disproportionately high frequency in patients hospitalized with atrial flutter. Male gender and a left ventricular ejection fraction < 40% are predictors of left atrial thrombus formation in such patients.

Audiometric changes following spinal anaesthesia.

A prospective study on audiometric changes following spinal anaesthesia with different gauge spinal needles was carried out in 125 patients; the patients were randomly divided into five groups according to gauge of needles used i.e., 20, 22, 23, 24 and 25 with twenty five patients in each group. Twelve percent and 8% decrease in audiometric values were recorded on first postoperative day at 250-500 Hz frequencies with 20 and 22 gauge needles respectively and these changes were highly significant (P < 0.001); these audiometric alterations returned to within normal limits by the 5th postoperative day. Eight percent decrease in audiometric values were observed on first postoperative day at 250-500 Hz frequencies with 23 gauge needle which was also statistically significant (P < 0.05); these changes returned to near normal limits by the 5th postoperative day. There was no significant decrease in the audiometric values following spinal anaesthesia with 24 and 25 gauge needles.

International comparative study of childhood malignancy comparative study of pediatric malignancy between Kurume and Karachi (K-K Project 1991).

UNLABELLED: A study was undertaken to compare Pediatric Malignancy at Kurume (Japan) and Karachi (Pakistan) with reference to international data collected over the years, in order to identify essential differences between developed and developing conditions and factors influencing the etio-pathogenesis of pediatric cancer. The study was retrospective encompassing all types of cancer in children over a period of three years i-e 1988-1990. Essential factors related to present study were: 1. POPULATION: The population of Karachi is about 10 million while that of Kurume is only half a million. 2. Socio-economic conditions: The average socio-economic condition of people in Karachi is poor while in Kurume it appears to be good. 3. Educational status: Only 25% people in Karachi are educated beyond middle class while Kurume reveals a 100% education up to high school level. 4. Environmental conditions: The environmental conditions of Kurume and surrounding areas are very clean and free from pollution, sewage problems and traffic hazards. Karachi and its surroundings on the other hand pose very serious air and water industries! It was concluded that whereas genetic predisposition predominates, the environmental conditions, educational and socio-economic status of a society immensely influence the pattern and trends of pediatric carcinogenesis.

Prospective study of changes in serum calcium after diethyl-ether anaesthesia.

Changes in serum calcium after diethyl-ether anaesthesia given for various routine surgical operations, were studied in 30 patients. Mean (+/- SD) concentration (mg%) of serum calcium before induction of anaesthesia was 10.37 +/- 0.77. Serum calcium decreased by 0.05 per cent after 10 min of induction and by 3.33 per cent at the end of anaesthesia which was highly significant (P less than 0.001). There was a correlation (r = 0.63; P less than 0.01) between decline in serum calcium and duration of ether anaesthesia. Serum calcium returned to near normal levels after 24 h of ether anaesthesia. In view of the fall in serum calcium, it is emphasized that ether should be either avoided in patients with known or suspected hypocalcaemia or be used for as short a time as possible with due precaution and calcium supplementation.