Colour stability of maxillofacial silicone elastomers: a review of the literature.

Colour degradation is a serious limitation of maxillofacial silicone elastomers and most silicone facial prostheses have to be remade within 1 year due to colour deterioration. A comprehensive review of the literature was completed using MEDLINE and PubMed Library databases. This was supplemented with a manual search of selected journals and textbooks. English language articles published in peer-reviewed journals from 1966 to January 2012 in which colour stability of silicone elastomers was evaluated using standard research protocols were included. In all, 127 articles were identified and 23 met the inclusion criteria. Current literature reveals that average colour stability of maxillofacial silicone prostheses is 6-12 months, and inherent unstable nature of silicones is responsible for the color degradation. Opacifiers, oil pigments and inorganic colourants may have a protective effect on colour stability of prostheses. Organic colourants, ultraviolet (UV) light, cleansing solutions, dust and aging can adversely affect colour stability of silicone prostheses. A direct comparison between studies has not been possible, because of the differences in experimental set-up such as materials tested, colourants used, or method of aging. There appears to be a need for a standardised test protocol for colour stability of maxillofacial materials. Colour degradation limits the useful lifespan of maxillofacial silicones. Improvements in colour stability is possible with the use of certain nano opacifiers, UV absorbers, photoprotective agents, and use of inorganic pigments and metal oxides.

Amitraz poisoning--an unusual pesticide poisoning.

AIMS OF THE STUDY: To report the clinical features, laboratory findings and the management instituted for the patients with acute Amitraz Poisoning. METHODS AND MATERIAL: Three cases of acute Amitraz Intoxication were studied and compared with previous reports from the literature. RESULTS: All the three female cases were brought to our hospital with age ranging from 2 years to 40 years, consumed poison by oral route. The ingested amount was ranging from 15 ml to 30 ml. Giddiness and vomiting were the prominent symptoms, next were drowsiness, irritability and respiratory distress. Two cases revealed gastric dilatation. Except hyperglycaemia and glucosuria other laboratory parameters were normal. Unconscious patient's CT brain revealed brain edema. One patient with hypotension improvement with i.v. fluids administration. All the patients recovered completely. DISCUSSION: Formamidines show toxic effects on both humans and animals. Amitraz is slightly toxic. Amitraz shows hepatotoxic, CNS stimulative or depressive effects. It can cause gastric stasis. Amitraz leads to rise in plasma glucose level and suppress insulin release. Decreased body temperature is due to inhibitory effect of Amitraz on Prostaglandin E2 synthesis. Even after poisoning by potentially lethal dose of Amitraz, studies have reported complete recovery. As there is no specific antidote for Amitraz Poisoning the medical management with O2 supplementation, airway maintenance, proper hydration and supportive management are the key factors for complete recovery of the patient. Public Health Education and instructions to drug producing companies will be necessary to decrease the incidence of Amitraz Poisoning.

New perspectives from microdialysis studies in freely-moving, spontaneously hypertensive rats on the pharmacology of drugs for the treatment of ADHD.

Attention deficit hyperactivity disorder (ADHD) is a common childhood psychiatric condition that is effectively treated by catecholaminergic drugs with a variety of different mechanisms and the SH rat is frequently used as a model of this disorder. In vivo microdialysis in freely-moving rats has been employed extensively to provide a better understanding of the pharmacodynamics of drugs at their sites of action. In this review, these three topics are brought together to explore the contribution of in vivo microdialysis studies in spontaneously hypertensive (SH) rats to our understanding of the neurochemical deficits in this rat strain and the actions of ADHD drugs on catecholaminergic function in the prefrontocortex (PFC), striatum and nucleus accumbens. What is revealed is that basal efflux of norepinephrine in the PFC is attenuated, whilst striatal and mesolimbic dopaminergic neurotransmission is hyperfunctional; the latter observation fits closely with the hyperactive phenotype of the SH rat. Furthermore, experiments performed with the enantiomers of amphetamine and threo-methylphenidate demonstrate that pharmacodynamic effects of drugs reported from experiments in outbred rat strains, e.g. Sprague-Dawleys, do not necessarily translate to the SH rat. When the findings are compared with the clinical efficacy of drugs used in treating ADHD, they indicate that the most efficacious drugs powerfully increase both norepinephrinergic and dopaminergic neurotransmission.

Role of cortisol on condition factor in the female freshwater fish, Notopterus notopterus during four reproductive phases.

The condition of the female fish, Notopterus notopterus was studied during four phases of the reproductive cycle in control and after cortisol hormone treatment. The condition of the fish including condition factor (K) and somatic condition factor (Ks) was determined based on weight of the body, length of the fish and gonad weight. In control fish the condition of the fish improve during prespawning phase compared to other phases. The hormone cortisol level estimated by radioimmunoassay (RIA) technique was found to be increased in preparatory and decreased during prespawning phase, may be because of the hormone involvement in metabolic activity, vitellogenesis. In cortisol treatment, the condition of the fish decrease during prespawning phase, compared to other phase may be because of extra expenditure of energy for progressing reproductive activity such as vitellogenesis.

Tissue cholesterol and serum cortisol level during different reproductive phases of the female freshwater fish Notopterus notopterus (Pallas).

In the present study tissue cholesterol and serum cortisol changes during two reproductive phases have been correlated in the freshwater fish Notopterus notopterus. The reproductive cycle of N. notopterus has two phases such as breeding phase (April - August) and non breading phase (October - December). The cholesterol content of the ovary and liver increased during breeding phase. The serum cortisol estimated by radio immuno assay (RIA) technique indicates that the level of the hormone was high during breeding phase compared to non breading phase. The increase in cholesterol during breeding phase may be because of increase in cortisol synthesis needed for ovarian growth and vitellogenesis. The gonadosomatic index (GSI) also increases during breeding phase.

Effect of cortisol on female freshwater fish Notopterus notopterus.

In the present study, effect of cortisol on the ovary of the freshwater fish Notopterus notopterus was studied during four phases of the reproductive cycle. The hormone was injected 60microg/fish for ten days. Cortisol in fish is known to increase the metabolic activity. After the hormone treatment the ovarian somatic index and the hepatosomatic index increases during non breeding phase. The young oocytes transferred into vitellogenic oocytes in all the phases after cortisol treatment. The cortisol induced increased ovarian activity may be due to increase in the metabolic activity through the involvement of hepatic cells specially during non-breeding period providing support for energy production for reproductive activity in the freshwater fish N. notopterus.

Fecundity of the freshwater fish, Notopterus notopterus (Pallas) in natural and heavy metal contaminated water.

The knowledge of fecundity of fish from a specific aquatic body is extremely important in the successful management and exploitation of its fishery. In the present investigation the fecundity of the freshwater fish, Notopterus notopterus was studied in fish collected from a natural aquatic body (Sirnoor nala) near Gulbarga and also in fish exposed to some heavy metal contamination (HgCl2, CdCl2 and their combination) at sublethal concentration for 15 days in the laboratory. The mathematical relationship between fecundity and total length, body weight, ovary length and ovary weight were determined in both unexposed and exposed fish. The fish, N. notopterus has bigger oocytes and are few in number. Studies in the fish exposed to heavy metals indicate that significant reduction in these parameters after exposure to heavy metals at sublethal concentration was noticed. The fecundity has straight line relationship with total length, body weight, ovary length and ovary weight in control fish which did not alter after heavy metal exposure. This study provides the viability of species in only specific environment.

Somatic condition of the fish, Notopterus notopterus (Pallas) during different phases of the reproductive cycle.

The study on the mathematical relationship between length and weight of fishes has considerable importance in fishery research especially for the study of fish population dynamics and patterns of growth in fish stocks. This aspect is useful in rationally managing the population of fishes, and is an index of relative robustness of the fish). Variations from expected weight or length of an individual fish or group of fish indicate the general well being and state of gonadal development. The condition of fish can be influenced by the onset of maturity. The results indicate that the overall condition of the female and male fish seems to get improved towards the approach of maturing and mature stages of the gonads during pre-spawning phases. The reduction in the condition factor (K) and somatic condition factor (Ks) during spawning phase may be because of the fish becoming exhausted due to spawning activity. Although improvement in the condition of the fish was observed on the approach of breeding period, the overall condition seems to be better in the aquatic body from which the fish was collected.

Resolution of DL-Phenylglycine by Penicillin G acylase.

The parameters for complete hydrolysis of L-phenyl acetyl phenylglycine (L-PAPG) using immobilized penicillin G acylase (IMEPGA) were investigated. IMEPGA exhibited maximum activity at pH 8.5 and 50 degrees C. The apparent Km value observed was 10 mM. Quantitative hydrolysis (>97%) of the L-PAPG was achieved within 45 min, at pH 7.8 and 37 degrees C, when 0.5% (w/v) of DL-PAPG was used and the concentration of IMEPGA was 133 IU/gm of DL-PAPG. The IMEPGA was used for 50 cycles.

Changes in tissue cholesterol and serum cortisol level during four reproductive phases of the male freshwater fish, Notopterus notopterus.

The tissue cholesterol and serum cortisol changes during four reproductive phases has been studied in the freshwater fish Notopterus notopterus of male sex during four phases, preparatory (January - March), prespawning (April - May), spawning (August - September) and post spawning (November - December). The cholesterol content of the testis and liver increased during preparatory phase and maximum content of cholesterol was during spawning phase. The serum cortisol estimated by radioimmunoassay (RIA) technique which indicated that the level of the hormone was high during pre-spawning and spawning phases compared to other two phases. The increase in cholesterol during preparatory and spawning phases may be because of increase in cortisol synthesis needed for testicular growth and spermetogenesis during these phases. The gonadosomatic index (GSI) also increased during these phases.

Gonadosomatic and hepatosomatic indices of the freshwater fish Notopterus notopterus (Pallas) in response to some heavy metal exposure.

Area wise, the measurement of LC50 for pollutants is of great value in predicting the safe concentration dose of the contaminant in the environment on different aquatic species. The lethality of toxic substances including heavy metals to the aquatic organisms are usually assessed by following static bio-assay or continuous flow methods. The toxicity tests for mercuric chloride (HgCl2), cadmium chloride (CdCl2) and their mixture on Notopterus notopterus was determined by using 96h LC50 concentration on fish N. notopterus which indicated that cadmium chloride (CdCl2) was less toxic and mercuric chloride (HgCl2) was most highly toxic. The order of toxicity is mercuric chloride > mixture > cadmium chloride. On the basis of gonadosomatic index the reproductive cycle of N. notopterus can be categorised into immature, developing, maturing, mature, ripe and spent stages. Liver forms important organ of the body, which has a role in the ovarian development. On exposure to heavy metals at sublethal concentration both GSI (gonadosomatic index) and HSI (hepatosomatic index) are reduced.

Ovarian changes in response to heavy metal exposure to the fish, Notopterus notopterus (Pallas).

The ovarian and hepatic protein, lipid and cholesterol content were estimated in the fish, N. notopterus after exposing it to heavy metals at sublethal concentrations. The protein, lipid and cholesterol content of ovary and liver got reduced and amongst the three exposures (mercuric chloride, cadmium chloride and their combination) it was significantly reduced in the order of (HgCl2>HgCl2>+CdCl2>CdCl2>control). The above results indicated that HgCl2 is highly toxic and its toxicity gets reduced in combination.

Fecundity of the freshwater fish Channa punctatus (Bloch) from three aquatic bodies.

The fecundity studies on Channa punctatus revealed that there is a relationship between length of the fish with fecundity, weight of the fish and ovary with fecundity. The length and fecundity exhibit curvilinear relationship and a straight line relationship is observed between fecundity and body weight. Fecundity and ovary weight also exhibited linear relationship. The comparative degree of fecundity of the fish is Jagat tank > Kadaganchi tank > Kagina river. Although fish collected from Jagat tank exhibits higher fecundity, all the other three aquatic bodies provide proper environmental conditions for the growth and reproductive activity of the fish.

Tomato leaf curl virus from Bangalore (ToLCV-Ban4): sequence comparison with Indian ToLCV isolates, detection in plants and insects, and vector relationships.

Tomato leaf curl virus (ToLCV) is a whitefly (Bemisia tabaci) transmitted geminivirus (family Geminiviridae, genus Begomovirus) causing a destructive disease of tomato in many regions of India, East Asia and Australia. While ToLCV isolates from Australia and Taiwan have a single genomic component (designated DNA-A), those from Northern India have two components (DNA-A and DNA-B). The ToLCV isolates from Southern India (Bangalore) previously cloned seem to have a DNA-A-like monopartite genome. We have used degenerate DNA-A-specific PCR primers to clone the genome of a ToLCV isolate (named ToLCV-Ban4) from field-infected tomato plants growing in Bangalore, India, in 1997. Degenerate DNA-B-specific PCR primers have not allowed to amplify a putative DNA-B from infected tomato, at the time when DNA-B fragments were amplified from plants infected by known bipartite begomoviruses. The full-length 2759 nucleotide-long DNA-A-like viral genome was sequenced. Similarly to other monopartite ToLCV and TYLCV isolates, ToLCV-Ban4 contains six open reading frames, two on the virion strand and four on the complementary strand. Sequence comparisons indicated that ToLCV-Ban4 is similar to the other three isolates from Bangalore previously sequenced, and is closely related to ToLCV-Ban2 (approximately 91% nucleotide sequence identity). Phylogenetic analysis showed that the ToLCV isolates from Bangalore constitute a group of viruses separated from those of Northern India. ToLCV-Ban4 was detected in tomato and in its whitefly vector Bemisia tabaci by one or by a combination of ELISA, Southern blot hybridization and PCR. Parameters of virus acquisition, retention and transmission by the whitefly vector were investigated in the laboratory. Single whiteflies were able to acquire ToLCV-Ban4 from infected tomato and to transmit the virus to tomato test plants, but five insects were necessary to achieve 100% transmission. Minimum acquisition access and inoculation access periods were 10 min and 20 min, respectively. A latent period of 6 h was required for B. tabaci to efficiently infect tomato test plants. Following a 24 h acquisition access period the insect retained its ability to infect tomato test plants for 12 days, but not for its entire life. In one insect/one plant inoculation tests, female whiteflies were more efficient (approximately 95%) than males (approximately 25%) in transmitting the virus.

Effect of cortisol on testis of freshwater fish Notopterus notopterus (Pallas).

Cortisol (20, 40 and 60 micrograms/fish for 10 days) treatment caused an increase in testicular-somatic index (TSI) in immature N. notopterus whereas in mature fish no change from that of controls was observed. Histology of testis indicated that spermatogenetic activity was activated in immature fish while it was inhibited in mature fish. Testicular cholesterol exhibited a similar response. The results indicate that cortisol inhibits spermatogenesis during mature phase while it promotes spermatogenesis during immature phase of the reproductive cycle in N. notopterus.

Bioremediation of epsilon-caprolactam from nylon-6 waste water by use of Pseudomonas aeruginosa MCM B-407.

Nylon-6, a man-made polymer that finds its application in the manufacture of car tires, ropes, fabrics, automobile parts etc., is manufactured with epsilon-caprolactam. Waste water generated during production of nylon-6 contains the unreacted monomer. Owing to the polluting and toxic nature of epsilon-caprolactam, its removal from waste streams is necessary. Pseudomonas aeruginosa MCM B-407 was isolated from activated sludge used to treat waste from a factory producing nylon-6. This organism was able to remove epsilon-caprolactam with simultaneous reduction in chemical oxygen demand (COD). The degradation of epsilon-caprolactam in waste water was found to be optimal over a wide range of pH from 5.0 to 9.0, temperature of 30 degrees C, and under shake or aerated conditions, with an inoculum density of 10(5) cells/ml and with an incubation period of 24 - 48 h. Thus, Pseudomonas aeruginosa MCM B-407 isolated from the activated sludge exposed to epsilon-caprolactam may play an important role in the bioremediation of epsilon-caprolactam from the waste waters of industries manufacturing nylon-6.

Bilateral cervical plexus block for thyroidectomy and parathyroidectomy in healthy and high risk patients.

We evaluated the benefits of bilateral deep cervical plexus block regional anesthesia in healthy and high risk patients undergoing thyroid and parathyroid surgery and assessed its effects on respiratory function. Twenty-one patients undergoing thyroid and parathyroid operations were studied. Bilateral superficial and deep plexus blocks were performed in all patients except one (who received only superficial plexus block because of a slightly prolonged prothrombin time) with 0.375-0.5% bupivacaine with 1:200,000 epinephrine. Intraoperatively, supplemental intravenous sedatives/narcotics were titrated to achieve patient comfort and cooperation. To allay anxiety, patients were allowed to listen to music via headphones intraoperatively. Forced vital capacity was measured before block, 10 minutes after the block and in the recovery room in half the patients. Eighteen patients tolerated the procedure well with supplemental sedation. Two patients required supplemental inhalation anesthesia via mask and one required tracheal intubation because of coughing prior to surgery. Three high risk patients tolerated the procedure well requiring only intraarterial line monitoring. Postoperatively, 11 patients had minimal incisional pain, 13 patients had mild pain on swallowing and 2 patients complained of nausea. There were no significant differences in the baseline forced vital capacity vs. forced vital capacity measured after the block and in the recovery room. This study indicates that regional anesthesia is an appropriate alternative to general anesthesia in selected patients undergoing thyroid and parathyroid surgery and did not compromise respiratory function.

Electrophysiological effects of propofol on the normal cardiac conduction system.

To determine the electrophysiological effects of propofol and to explain the potential mechanism(s) whereby it causes bradyarrhythmias, 10 closed-chest pigs weighing 20-25 kg were studied. Each animal was premedicated by intramuscular administration of ketamine hydrochloride, intubated, and mechanically ventilated. Femoral arterial and venous catheters were placed, and a comprehensive electrophysiologic evaluation was performed at baseline and after two doses (1 mg/kg i.v. bolus and 0.1 mg/kg/min infusion and an extra 1- mg/kg i.v. bolus and 0.2 mg/kg/min infusion) of propofol. The electrophysiological effects obtained on low-and high-dose propofol were compared to baseline values. Propofol caused a dose-related decrease in sinus cycle length (baseline 565 +/- 36 ms, low-dose propofol 541 +/- 28, high-dose propofol 527 +/- 26 ms; p < 0.05), a prolongation of the corrected sinus node recovery time (baseline 119 +/- 35 ms, low-dose propofol 126 +/- 32, high-dose propofol 130 +/- 30 ms; p < 0.01), and an increase in the His-ventricular interval (baseline 33 +/- 4 ms, low-dose propofol 36 +/- 4, high-dose propofol 40 +/- 3 ms; p < 0.005). All other electrophysiological parameters remained unchanged, and there were no cases of spontaneous atrioventricular block or sinus pauses. We conclude that propofol causes dose-related depression of sinus node and His-Purkinje system functions, but has no effect on the atrioventricular node function and on the conduction properties of atrial and ventricular tissues in normal pig hearts.

Inhibitory effects of ketamine and halothane on recombinant potassium channels from mammalian brain.

BACKGROUND: There is increasing evidence that direct interactions between volatile anesthetics and channel proteins may result in general anesthesia. Using voltage-clamp techniques, the authors examined the effect of two general anesthetics (ketamine and halothane) on a rat brain potassium channel of known amino acid sequence, and further assessed whether the inhibition of the channel is altered by a partial deletion of the C-terminal sequence of this channel. METHODS: Xenopus laevis oocytes were microinjected with either Kv2.1 or delta C318 (a mutated channel in which the last 318 amino acids of the C-terminus have been deleted) cRNA, and channel function in translated channels was observed before, during, and after exposure to graded concentrations of ketamine (25, 50, and 75 micrometers) and halothane (1%, 2%, and 4%). RESULTS: Ketamine and halothane reduced Kv2.1 and delta C318 peak current amplitude in a dose-dependent and reversible fashion. The inhibition of current was voltage dependent for halothane but not for ketamine. Halothane accelerated the time constant of current inactivation, whereas ketamine affected this parameter minimally in both channel types. Use dependence of ketamine and halothane action was observed in both Kv2.1 and the mutant channel, attributable to augmentation of C-type inactivation. CONCLUSIONS: Although both ketamine and halothane inhibit potassium currents through the Kv2.1 channel, their mechanisms of action at this potential target may be different. Deletion of the C-terminal sequence resulted in decreased sensitivity to both anesthetics. Although it is not clear whether anesthetics interact directly with the C-terminus, which is thought to reside intracellularly, this portion of the channel protein clearly influences the actions of both anesthetics.