Fast and scalable layer four switching

In Layer Four switching, the route and resources allocated to a packet are determined by the destination address as well as other header fields of the packet such as source address, TCP and UDP port numbers. Layer Four switching unifies firewall processing, RSVP style resource reservation filters, QoS Routing, and normal unicast and multicast forwarding into a single framework. In this framework, the forwarding database of a router consists of a potentially large number of filters on key header fields. A given packet header can match multiple filters, so each filter is given a cost, and the packet is forwarded using the least cost matching filter .In this paper, we describe two new algorithms for solving the least cost matching filter problem at high speeds. Our first algorithm is based on a grid-of-tries construction and works optimally for processing filters consisting of two prefix fields (such as destination-source filters) using linear space. Our second algorithm, cross-producting, provides fast lookup times for arbitrary filters but potentially requires large storage. We describe a combination scheme that combines the advantages of both schemes. The combination scheme can be optimized to handle pure destination prefix filters in 4 memory accesses, destination-source filters in 8 memory accesses worst case, and all other filters in 11 memory accesses in the typical case.

Composition of gallstones in Coimbatore District of Tamil Nadu State

BACKGROUND

Gallstones in northern India are predominantly of the cholesterol type; such information on gallstones in southern India is scant.

AIM

To analyze the composition of gallstones from patients residing in Coimbatore District in Tamil Nadu State.

METHODS

The stones were classified using the Bernhoft criteria and was correlated with the morphological characteristics.

RESULTS

Of the 105 gallstones analyzed, 67 (63.8%) were of the pigment variety and 36 (34.8%) of the intermediate/mixed type. There were only two cholesterol stones. The mean proportions of cholesterol, bilirubin and calcium in the pigment and intermediate stones were 7.1%, 26.1% and 7.8% and 30.2%, 18.4% and 6.3%, respectively. The mean proportion of bilirubin in the pigment stones was higher than in the intermediate type. Morphologically, pigment stones were black in 55% and amorphous in 63%; the intermediate stones were hard in 50% and of variegated color ranging from yellow to ivory white in 61%; both cholesterol stones were multiple, hard and brown.

CONCLUSIONS

There is a predominance of pigment and intermediate gallstones (98%) in this district. These stones have reduced cholesterol and an increase in bilirubin and calcium proportions.

An unusual presentation of a nasal septal abscess

Nasal septal abscess is a rare complication of septal haematoma. Nasal obstruction and, less frequently, pain are the usual presenting features. We report a case of a nasal septal abscess in a 21-year-old female patient who developed a naso-oral fistula. To our knowledge this is the first report of such an unusual presentation of a septal abscess. The aetiology, pathogenesis and management of septal abscesses are discussed.

Use of a disposable electrode for recurrent laryngeal nerve monitoring

Our experience with a non-invasive, disposable electrode for intra-operative identification and monitoring of the recurrent laryngeal nerve is described. The electrode system, while simply attached to the endotracheal tube, acts as a laryngeal surface electrode and detects electromyographic activity of the intrinsic laryngeal muscles when the recurrent laryngeal nerve is stimulated. We have successfully used this electrode to monitor 19 recurrent laryngeal nerves in 15 patients who have undergone partial or total thyroidectomy. We feel that this device can be useful particularly in cases of re-exploration and malignancies of the thyroid gland.

Differences in active avoidance behaviour of hypoactive and hyperactive rats subjected to immobilisation stress

Open field activity was studied in Wistar rats. Animals with low scores of ambulatory and rearing behaviours were grouped as hypoactive and those with high scores as hyperactive. Acquisition of active avoidance learning in a shuttle box was studied in the two groups. Hyperactive rats in contrast to hypoactive rats showed a better acquisition of avoidance learning. Learning was suppressed in both groups by domperidone, but was facilitated by immobilisation stress in the hypoactive group only. The two groups did not differ in the basal and stress evoked heart rates. These observations suggest that immobilisation stress favours enhancement of the dopaminergic related behaviour like avoidance learning in hypoactive rats.

Is vegetarianism a precipitating factor for gallstones in cirrhotics?

AIM

To study the association of factors such as alcohol, smoking and vegetarianism with presence of gallstones amongst cirrhotics.

PATIENTS AND METHODS

Data on alcoholism, smoking and vegetarianism was collected from the case records of 669 cirrhotics with (76) or without gallstones (593) retrospectively. Relative risk for the factors was computed individually and in combination controlling for the effects of alcoholism and smoking on vegetarianism.

RESULTS

Alcoholism and smoking were of low relative risk [R.R-1.27 (95% CI 0.82 to 1.96), and 1.02 (95% CI 0.65 to 1.61) respectively] while vegetarianism was associated with high risk for gallstone formation in cirrhotics [R.R 2.74 (95% CI 1.65-4.53)]. Vegetarian men had a relative risk of 3.02 (95% CI 1.75-5.22) irrespective of their alcoholic status. If women were alcoholic the relative risk increased to 7.03 (95% CI 3.26-15.12). Controlling for effects of gender and alcoholism, vegetarian cirrhotics had a 3 times greater risk for gallstone formation [Mantel Haenszel Relative Risk 3.18 (95% CI MHRR 1.82-5.56)].

CONCLUSIONS

Cirrhotic, vegetarian women in South India have a much higher risk for gallstones, if they are alcoholic. Alcoholic men who are vegetarians are at a greater risk for gallstone disease.

Warfarin and epistaxis: should warfarin always be discontinued?

The object of this study was to determine whether warfarin could be safely continued in patients with epistaxis if the International Normalized Ratio (INR) was within the suggested therapeutic range. Twenty patients on warfarin treatment were compared with controls, matched for age and sex. Local measures for the control of epistaxis were undertaken appropriately in all the patients. In the warfarin group 17 patients (85%) did not discontinue warfarin as the INR was within the suggested range. There were no additional bleeding complications or failure of epistaxis control due to continuation of warfarin. There was no significant difference in the mean hospital stay between the warfarin and non-warfarin groups. It is concluded that warfarin can be continued safely in patients with epistaxis, in appropriate circumstances, and that the policy of stopping warfarin routinely in all patients with epistaxis should be reconsidered.

Melatonin, biological rhythm disorders and phototherapy

Biological rhythms are endogenous in nature and are generated by self sustained oscillators present in the living organisms themselves. Of these, circadian rhythms are the most thoroughly studied and are driven by the suprachiasmatic (SCN) of hypothalamus. The recent discovery of high affinity melatonin receptors ML1, ML2 in SCN suggests that melatonin is involved in the control of circadian rhythm generation. The fact that biological rhythm disorders like delayed sleep phase syndrome (DSPS), Jet lag, shift-work disorders, seasonal effective disorder (SAD) respond well either to phototherapy or melatonin adds further support to the concept that melatonin is involved in the pathogenesis of these conditions. Indeed altered melatonin rhythms have bee documented in MDP, shift work disorder, endogenous depression etc. In addition to functioning as a rhythm regulator, melatonin is also involved in the control of sleep, regulation of body temperature, reproduction, and as a free radical scavanger and antioxidant protecting the cells and tissues of our body against oxidative damage. Low levels of melatonin in cancer patients and patients with coronary heart disease indicate that melatonin may be involved in these disorders also.

Combined use of six-well polystyrene plates and thin layer chromatography for rapid development of optimal plant cell culture processes: application to taxane production byTaxus sp

TwoTaxus (T. chinensis andT. baccata) cell suspension cultures were used as a model system to demonstrate the similarities of biomass accumulation and secondary metabolite (taxane) production obtained from cultures in six-well polystyrene plates and glass shake flasks (25 ml and 125 ml). Interference from binding of taxanes in cell-free culture broth to the polystyrene plates was minimal with 85% of the paclitaxel (Taxol®) and 100% of baccatin and 10-deacetyl-7-xylosyl-taxol remaining in the medium after 24 h beyond which no further binding was observed. A simple thin layer chromatography (TLC) procedure with a chloroform: acentonitrile (4:1) solvent system on silica gel was developed to simultaneously test up to 17 cultures for taxane production. The combination of six-well plate technology for experimentation and TLC for rapid taxane analysis can greatly accelerate the establishment of conditions for an optimalTaxus plant-cell culture process for taxane production.

Transtympanic myringoplasty in children

Our experience with myringoplasty by the transtympanic "push through' technique in paediatric patients is described. We have used this method in 40 children utilizing autologous temporalis fascia as the graft material. The procedures were all performed as day cases under general anaesthesia. The overall success rate for perforation closure was 77.5% at 6 months which is comparable to conventional methods. We conclude that the "push-through' technique is a safe, simple, reliable and cost-effective procedure that can be performed as a day case in paediatric patients. It avoids the necessity for pressure bandaging or formal ear packing. To our knowledge this is the first paper evaluating this technique in children.

Non-recurrent laryngeal nerve: identification during thyroid surgery

The non-recurrent course of the inferior laryngeal nerve is a rare anomaly. The incidence varies from 0.3 to 4% on the right side. It is extremely rare on the left side. The awareness of such an anomaly is essential as the risk of damage to the nerve is higher during thyroid surgery. Two cases of non-recurrent laryngeal nerve are reported, and the embryology and method of identification are discussed.

Influence of respiration on human sympathetic skin response

Sympathetic skin response (SSR) is a reflexly elicited potential of the sweat glands, the afferent and efferent fibres of the reflex are cutaneous sensory fibres (if the SSR is elicited by electrical stimulus) and sympathetic sudomotor fibres respectively. Our earlier study indicated that latency, besides duration and amplitude, of SSR of a given normal individual showed significant variations between many trials of stimulation, even in a single sitting. Since deep inspiration is also an effective stimulus to elicite SSR, the present study was conducted to assess the influence of respiration on SSR. Thirty-four healthy students participated in the study. The skin of the forearm of the dominant hand was stimulated by electrical square pulse and SSR was recorded from the ipsilateral hand. SSR was elicited and recorded in each subject during the various phases of respiration, namely, end expiration (EE), end inspiration (EI), mid expiration (ME) and mid inspiration (MI). It was observed that the mean values of SSR latency during these respiratory phases (EE : 1.59, EI: 1.51, ME : 1.55, and MI: 1.56 sec) were similar, indicating that the normal respiration might not be responsible for the observed interstimulation variations in latency in any given individual.

Comparative evaluation of cine-esophagogram with esophageal manometry in assessing esophageal motility in progressive systemic sclerosis

BACKGROUND

Esophageal manometry is considered the gold standard in the diagnosis of esophageal motility disorders. Cine-esophagogram using barium is also a good investigation to screen patients for motor disorders of the esophagus. Comparison between these two investigations has not often been reported in patients with progressive systemic sclerosis (PSS).

AIM

To determine relative merits of cine-esophagogram and esophageal manometry in detecting esophageal motor dysfunction in PSS patients.

METHODS

Thirty-five patients with PSS irrespective of esophageal symptoms underwent esophageal manometry and cine-esophagogram, results and their were compared.

RESULTS

Sensitivity and specificity of cine-esophagogram as compared to manometry were 96.1% (95% CI 88.7%-100%) and 55.5% (95% CI 23%-87.9%) respectively. Its positive predictive value was 86%.

CONCLUSION

While esophageal manometry can identify esophageal motor disorder in PSS, cine-esophagogram can be resorted to in doubtful situations, for confirmation of diagnosis.

Quantitative description of the effect of molecular size upon electroosmotic flux enhancement during iontophoresis for a synthetic membrane and human epidermal membrane

This study focused upon quantitatively determining the influence of permeant molecular size upon flux enhancement which results from electroosmosis. The first phase of the study involved validation of a fundamental model describing the molecular size dependence of flux enhancement which results from convective solvent flow. This was accomplished using a model synthetic membrane (stack of 50 Nuclepore membranes) and four model permeants with a molecular weight range of 60-504 (urea, mannitol, sucrose, and raffinose). The steady-state flux of each permeant was determined under passive conditions and applied voltages of 125, 250, 500, and 1000 mV using side-by-side diffusion cells and a four-electrode potentiostat system. On the basis of the permeability enhancement for each permeant at each applied voltage (relative to the passive permeability) it was possible to calculate the effective solvent flow velocity from each permeant at each field strength. An important finding was that the flux enhancement due to electroosmosis was strongly molecular weight dependent (i.e., the flux enhancement ratio was around 4 times greater for raffinose than for urea, with mannitol and sucrose yielding intermediate values), while the calculated effective flow velocity at each voltage was independent of the molecular weight of the permeant. This coupled with a linear correlation between flow velocity and applied voltage served to establish the validity of the method and model. The second phase of the study was an extension of the model to human epidermal membrane (HEM). These experiments involved simultaneously measuring the fluxes of [14C]urea and [3H]sucrose across HEM samples under passive, 250 mV, and 500 mV conditions. Similar to the Nuclepore system, the observed flux enhancement ratios with HEM were approximately 3 times greater for sucrose than for urea. A detailed analysis of the HEM data showed semiquantitative agreement between predictions of the model and experimental results.