Photonic ring resonator filters for astronomical OH suppression.

Ring resonators provide a means of filtering specific wavelengths from a waveguide, and optionally dropping the filtered wavelengths into a second waveguide. Both of these features are potentially useful for astronomical instruments. In this paper we focus on their use as notch filters to remove the signal from atmospheric OH emission lines from astronomical spectra. We derive the design requirements for ring resonators for OH suppression from theory and finite difference time domain simulations. We find that rings with small radii (< 10 µm) are required to provide an adequate free spectral range, leading to high index contrast materials such as Si and Si3N4. Critically coupled rings with high self-coupling coefficients should provide the necessary Q factors, suppression depth, and throughput for efficient OH suppression, but will require post-inscription tuning of the coupling and the resonant wavelengths. The overall prospects for the use of ring resonators in astronomical instruments is promising, provided efficient fibre-chip coupling can be achieved.

Embolic phenomena during computer-assisted and conventional total knee replacement.

Systemic emboli released during total knee replacement have been implicated as a cause of peri-operative morbidity and neurological dysfunction. We undertook a prospective, double-blind, randomised study to compare the cardiac embolic load sustained during computer-assisted and conventional, intramedullary-aligned, total knee replacement, as measured by transoesophageal echocardiography. There were 26 consecutive procedures performed by a single surgeon at a single hospital. The embolic load was scored using the modified Mayo grading system for echogenic emboli. Fourteen patients undergoing computer-assisted total knee replacement had a mean embolic score of 4.89 (3 to 7) and 12 undergoing conventional total knee replacement had a mean embolic score of 6.15 (4 to 8) on release of the tourniquet. Comparison of the groups using a two-tailed t-test confirmed a highly significant difference (p = 0.004). This study demonstrates that computer-assisted knee replacement results in the release of significantly fewer systemic emboli than the conventional procedure using intramedullary alignment.

Simulation of normal, carrier and affected controls for large-scale genotyping of cattle for factor XI deficiency.

An insertion mutation within exon 12 of the factor XI gene has been described in Holstein cattle. This has opened the prospect for large-scale screening of cattle using the polymerase chain reaction (PCR) technique for the rapid identification of heterozygous animals. To facilitate such a screening process, the mutant and normal alleles of factor XI gene, represented by 244- and 320-bp PCR amplified fragments, were individually cloned in Escherichia coli using a multicopy plasmid cloning vehicle to generate pFXI-N and pFXI-M, respectively. The authenticity of the inserts was confirmed by nucleotide sequencing. A nested PCR method was developed, by which PCR amplicons generated from primers with annealing sites on the recombinant plasmids and by flanking the insert were used as templates for amplification of the diagnostic products using factor XI gene-specific primers. An equimolar mixture of both PCR amplicons, originating from pFXI-N and pFXI-M, constituted the carrier control while the individual amplicons were the affected and normal controls. The controls were used as references for in-gel comparison to screen a population of 307 cattle and 259 water buffaloes; the frequency of the mutant allele was found to be 0. No DNA size standards were required in this study. The simulated control DNA samples representing normal, carrier and affected cattle have the potential to help in large-scale screening of a cattle population for individuals that are carriers or affected by factor XI deficiency.

Medical students' self-confidence in performing direct ophthalmoscopy in clinical training.

BACKGROUND: Although direct ophthalmoscopy is an important skill that medical students must practice to gain proficiency, limited time is generally available in medical school curricula. More targeted and effective teaching could result from a clearer understanding of medical students' self-reported needs and weaknesses in performing direct ophthalmoscopy. METHODS: A cross-sectional survey was conducted at a Canadian university to determine the confidence of medical students in their skill in performing direct ophthalmoscopy. The responses of 208 participants who volunteered to complete a 21-item questionnaire were analyzed. RESULTS: Although clerks were significantly more confident in their overall skill (chi2=28.03, p<0.001) than were first- and second-year students, 47% of clerks were "not at all" or only "a little" confident in performing direct ophthalmoscopy on an undilated pupil. Respondents who had practiced on more than 10 occasions outside of formal teaching were significantly more confident in their overall skill than those who had not (chi2=22.94, p<0.001). Overall, 87% (77% of clerks) were "quite" or "extremely" interested in more practice and training on direct ophthalmoscopy. INTERPRETATION: A large proportion of medical students reported not being confident in various aspects of their skill in performing direct ophthalmoscopy. Self-confidence was significantly greater among students who practiced outside of formal teaching sessions. Most students were interested in additional training, and medical schools should emphasize the importance of practicing whenever appropriate.

Estrogen modulates sexually dimorphic contextual fear conditioning and hippocampal long-term potentiation (LTP) in rats(1).

The present study examined the role of ovarian steroids in contextual fear conditioning and hippocampal synaptic plasticity in female rats. In experiment 1, adult female rats were ovariectomized and submitted to contextual fear conditioning, a procedure in which rats received unsignaled footshock in a novel observation chamber; freezing behavior served as the measure of conditional fear. Ovariectomized female rats froze at levels comparable to male rats, both of which froze significantly more than sham-operated female rats. In experiment 2, estrogen replacement in ovariectomized female rats reduced fear conditioning to a level comparable to that of sham-operated females in experiment 1. In experiment 3, the influence of estrogen on the induction of long-term potentiation (LTP) at perforant path-dentate granule cell synapses in ovariectomized female rats was examined. Estrogen decreased both population spike LTP and EPSP-spike potentiation at perforant path synapses. Taken together, these experiments indicate that ovarian steroids regulate both sexually dimorphic behavior and hippocampal plasticity in a fear-conditioning paradigm.

Traumatic phacocele.

We report a case of traumatic phacocele in a 42-year-old patient with a history of congenital glaucoma and bilateral goniotomies as an infant. Her left eye had little vision and poorly controlled intraocular pressure but was comfortable until her presentation after blunt trauma. Phacocele or subconjunctival dislocation of the crystalline lens is a rare consequence of blunt trauma, particularly in a patient whose only previous ocular surgery was goniotomy more than 40 years ago.

The primary in vitro anticancer activity of "half-mustard type" phenothiazines in NCI's revised anticancer screening paradigm.

Some new phenothiazines have been synthesized on the basis of previous studies. The anticancer activity of "half-mustard type" phenothiazines was investigated on sixty different cancer cell lines in vitro. The percentage of growth (PG), 50% inhibition of growth (GI50), the tumor growth inhibition (TGI) and the concentration required for 50% lethality of cells (IC50) were examined and calculated in the presence of various (from 10(-4) to 10(-8) M) concentrations of phenothiazine alkylurea derivatives. The following cell lines were involved in the study: 6 leukemia, 9 non-small-cell lung cancer, 7 colon cancer, 6 central nervous system cancer, 8 melanoma, 6 ovarian cancer, 8 renal cancer, 2 prostate and 8 breast cancer cell lines. The antileukemic activity of four chloroethyl-substituted phenothiazine-alkylureas was shown by considerable growth inhibition, in the 10(-5) M range, of the six different leukemia cell lines. The 50% inhibition of growth was nearly the same for the four compounds on all cell lines. Tumor growth inhibition (TGI) and IC50 value to cells varied from -4.0 to -4.66. The two derivatives with the butylene bridge were more effective than propylene linked compounds against the CCRP-CEM, HL60 (TB), K-562 and MOLT-4 cell lines. However, the anti-leukemic activity of the derivatives was nearly the same for RPMT 8226 and SR cell lines. The substituent at the 2- position of phenothiazine ring and the length of the linker between the side chain nitrogen and the phenothiazine ring system are apparently important for antileukemic activity. Four of the 9 non-small-cell lung cancer cell lines were sensitive, while the other 5 cell lines were not. The compounds had a slight growth inhibitory effect on colon cell carcinoma and melanoma cells in which case the butylene linker seemed to be more effective than the propylene linker. At the same time, all of the compounds were weak or mostly inactive on cancer cells from the central nervous system. One ovarian cancer line of the 6, the IGROVI was sensitive to butylurea phenothiazines, however, the other five were not sensitive at all. The difference in the sensitivity of various renal cell carcinomas was significant: 5 lines were not sensitive, three of them (786-0, RXF-393 and TK-10) were sensitive to only butylene-substituted phenothiazine-ureas, propylene substitution resulted in ineffective compounds. The compounds were not able to inhibit the 2 prostate and 4 breast cancer cell lines, even at 10(-4) M. It was interesting that propylene-linked ureas were more effective than butylene-linked derivatives on MCF-7, but butylene-linked derivatives were more effective than propylene-linked compounds on MDA MB-231 and MDA-N. In addition, MDA MB 435 was more sensitive to the trifluoromethyl derivatives than the compounds without this substituent. Since the phthalimido-alkyl phenothiazines were not active at the first level of prescreen, these compounds were omitted from this study. The drug sensitivity of some cancer cell lines was not uniform for the different groups, therefore we postulate that the resistance can be related to some kind of (existing) drug-efflux mechanism. Apparently, the tumor specificity of phenothiazine alkylureas is more related to the leukemia specificity of alkylureas than to any CNS or lung specificity of phenothiazines.

Intracorporeal or extracorporeal lithotripsy for distal ureteral calculi? Effect of stone size and multiplicity on success rates.

Over a period of 57 months, 404 patients with distal ureteral calculi were treated by in situ SWL on a Storz Modulith SL 20 lithotripter and 163 by ureteroscopy (URS) and Swiss Lithoclast stone fragmentation. The case notes on these patients were reviewed for comparison of the initial stone number and individual length and for the calculation of the stone-free, treatment, retreatment, secondary procedure, and complication rates. Complete data were available on 447 patients. The median stone length was 7.0 (range 4-25) mm in the SWL group and 8.0 (range 5-13) mm in the URS group. The single-treatment stone-free rates for the SWL and URS groups were 74.8% and 89.7%, respectively, for single stones and 50.0% and 88.9%, respectively, for multiple (>1) stones. The mean treatment rates for the SWL and URS groups were 1.97 and 1.03, respectively, for single stones and 2.83 and 1.00, respectively, for multiple stones. The mean treatment rate for single stones subjected to SWL increased with increasing stone length (1.57 for stones <8 mm and 2.38 for stones >8 mm), whereas this was not the case for patients submitted to URS (1.20 and 1.27, respectively). The re-treatment rate for each group showed a reciprocal trend. Of the SWL group, 25.9% of the patients eventually required URS to render them stone-free. Nearly all (96%) of the patients undergoing SWL were treated as outpatients. The mean hospitalization in the URS group was 1.1 days. Three patients who underwent URS sustained a ureteral perforation, which was managed successfully by double-J stent insertion. The ideal primary treatment for small (<8 mm) distal ureteral calculi is in situ SWL, with URS plus Lithoclast fragmentation being reserved for failed SWL, single stones >8 mm in length, and multiple stones.

Lipid-lowering efficacy of psyllium hydrophilic mucilloid in non insulin dependent diabetes mellitus with hyperlipidaemia.

The effect of the administration of 3.5 g of psyllium husk twice daily for 90 days was investigated in 24 patients of non insulin dependent diabetes mellitus (NIDDM) with hyperlipidaemia. After 90 days of treatment, psyllium was withdrawn and the patients were followed up for a further 90 days. Psyllium significantly decreased the levels of total cholesterol (TC; 19.7%), low-density lipoprotein cholesterol (LDL-C; 23.7%), triglycerides (TG; 27.2%) and the ratio of LDL-C to high-density lipoprotein cholesterol (HDL-C; 24.1%) and the lowering was sustained even up to 90 days after cessation of treatment. The level of HDL-C also showed a significant increase of 15.8 per cent but this effect was not sustained after cessation of treatment. The compliance was very good and no adverse effects were observed. This study indicated that psyllium husk is an effective and well tolerated adjunct to diet for the treatment of mild to moderate hyperlipidaemia in NIDDM patients.

Development of differential cytotoxic compounds containing nitrosourea and benzothiazine nucleus.

The in vivo activity of 4 new benzothiazinyl-nitrosourea compounds was investigated against Sarcoma-180 (S-180) and Ehrlich Ascitic Carcinoma (EAC) induced ascitic and solid tumors. EAC solid tumor was found to be the most sensitive, where one compound (no 4) inhibited tumor growth to only 3 per cent of the control value. All the 4 compounds tested were found to be toxicologically more selective than 5-fluorouracil and 6-mercaptopurine drugs. The reason for this selective toxicity may be attributed to the inhibition of isocyanate moiety in these compounds which causes toxicity to normal cells via a carbamoylation reaction. However, they may still remain potent, since they decompose into an alkylating carbonium species and a charge transfer complex which may interact with DNA via alkylation and intercalation reactions, respectively.

Role of H-reflex latency studies in the diagnosis of subclinical diabetic neuropathy.

Motor conduction velocity (MCV) in the median, ulnar and peroneal nerves and H-reflex studies have been conducted in 50 diabetics aged 20-65 years and 25 controls. MCV in the upper limb was below the normal range in 16% of diabetics. 28% diabetics showed abnormal MCV in the peroneal nerve. H-reflex abnormality consisting of either prolonged latency or its complete absence could be observed in 54% of diabetics. The results indicate the greater sensitivity of H-reflex in the detection of sub-clinical diabetic neuropathy. Greater prevalence of neuropathy in the early onset diabetes than in the late onset type is also suggested.