Magnetic characterization of radio frequency heat affected micron size Fe3O4 powders: a bio-application perspective

Micron size Fe3O4 powders were chemically prepared and processed by radio frequency (13.56 MHz) oxygen plasma irradiation technique at different elevated temperatures using low radio frequency (RF) power level. Low magnetic field RF superconducting quantum interference device (SQUID) magnetization studies were performed up to a maximum magnetic field of 100 Oe, which was well below the magnetic field tolerance factor of human beings and at different temperatures (down to 5 K). Heat-treated powders in RF oxygen plasma showed significant changes in blocking temperature, magnetization and susceptibility, which are important parameters for bio-applications. It is observed that blocking temperature is decreased under identical RF heat treatment in oxygen plasma and noted to be dependent on average particle size. Microscopic rise in electron temperature during RF heating may likely to enhance the electron-hopping rate between Fe(+2) and Fe(+3) in the octahedral site of Fe3O4 molecular crystal structure, which in turn exhibit changes in blocking temperature including low field magnetization and susceptibility. These properties of Fe3O4 fine powder are likely to play important role in generating and processing biocompatible Ferro-fluid down to nanoscopic size for biomaterials applications.

Influences of reduced expression of maternal bone morphogenetic protein 2 on mouse embryonic development

Bone morphogenetic protein 2 (BMP2) was originally found by its osteoinductive ability, and recent genetic analyses have revealed that it plays critical roles during early embryogenesis, cardiogenesis, decidualization as well as skeletogenesis. In the course of evaluation of the conditional allele for Bmp2, we found that the presence of a neo cassette, a selection marker needed for gene targeting events in embryonic stem cells, in the 3' untranslated region of exon 3 of Bmp2, reduced the expression levels of Bmp2 both in embryonic and maternal mouse tissues. Some of the embryos that were genotyped as transheterozygous for the floxed allele with the neo cassette over the conventional null allele (fn/-) showed a lethal phenotype including defects in cephalic neural tube closure and ventral abdominal wall closure. The number of embryos exhibiting these abnormalities was increased when, due to different genotypes, expression levels of Bmp2 in maternal tissues were lower. These results suggest that the expression levels of Bmp2 in both embryonic and maternal tissues influence the normal neural tube closure and body wall closure with different thresholds.

Expression profiling of human donor lungs to understand primary graft dysfunction after lung transplantation

Lung transplantation is the treatment of choice for end-stage pulmonary diseases. A limited donor supply has resulted in 4,000 patients on the waiting list. Currently, 10-20% of donor organs offered for transplantation are deemed suitable under the selection criteria, of which 15-25% fail due to primary graft dysfunction (PGD). This has spawned efforts to re-examine the current selection criteria as well as search for alternative donor lungs selection criteria. In this study, we attempt to further our understanding of PGD by observing the changes in gene expression across donor lungs that developed PGD versus those that did not. From our analysis, we have obtained differentially expressed transcripts that were involved in signaling, apoptosis and stress-activated pathways. Results also indicate that metallothionein 3 was over expressed in lungs that didn't develop PGD. This is the first such attempt to perform expression profiling of actual human lungs used for transplantation, for the identification of a molecular signature for PGD.

Family-based association analysis of functional VNTR polymorphisms in the dopamine transporter gene in migraine with and without aura

Because of the role of dopamine in triggering migraine attacks, genes of the dopamine system are candidates for involvement in migraine. We examined three VNTR polymorphisms in the dopamine transporter, the 5'UTR VNTR, the intron 8 VNTR and the intron 14 VNTR, in a sample of 205 family trios. We used the transmission disequilibirium test (TDT) to examine the transmission of these three markers and their haplotypes to offspring affected by migraine. We found no significant transmission distortion of any marker. Likewise haplotypes of the three markers did not show significant overall or individual association with migraine. Finally we examined migraine with and without aura, and likewise found no association between dopamine transporter VNTRs or their haplotypes and either classification of the disease. We conclude that functional genetic variation in the dopamine transporter does not act as a significant risk factor for migraine.

Hashimoto's encephalopathy in an adolescent boy

Hashimoto's encephalopathy is an under-recognized cause of acute encephalopathy both in children and adults. We hereby describe a 12.5 yr old boy with this rare disorder that presented with an acute onset of episodic psychosis with hallucinations along with seizures and had elevated antithyroid antibodies. Symptoms improved with thyroxine replacement and anticonvulsants and EEG normalized 3 mth into follow up. Hashimoto's encephalopathy should be considered in patients with unexplained encephalopathy and seizures, as prompt recognition and management can lead to an excellent outcome.

Platelet and leukocyte activation in salvaged blood and the effect of its reinfusion on the circulating blood

Postoperative wound drainage reinfusion reduces the frequency of homologous blood transfusion. The salvaged blood is depleted of coagulation factors but may contain platelets and leukocytes which are activated, and therefore potentially procoagulant. We ascertained the degree of activation of platelets and leukocytes in salvaged blood and asked whether their infusion produced any measurable effect on patients' coagulation system. We prospectively randomized 24 patients who had total knee arthroplasties to reinfusion of salvaged autologous blood (n = 12) or a standard drain with no reinfusion (n = 12). Analysis of the salvaged blood showed marked activation of platelets as shown by their expression of P-selectin, CD40 ligand, and Factor V/Va, and as increased numbers of platelet-derived microparticles. After reinfusion there was no measurable effect on activation markers of circulating platelets or leukocytes but there was a decrease in platelet count in the reinfused group compared with the control group. Levels of prothrombin fragment F1 + 2 (suggesting thrombin formation) increased in the reinfused group compared with control group, possibly indicating activation of coagulation systemically. The platelets and leukocytes in salvaged blood are markedly activated and their reinfusion causes a decrease in platelet count in the recipient and a possible increase in thrombin generation potentially favoring thrombosis.

Aprotinin and epsilon aminocaproic acid are effective in reducing blood loss after primary total hip arthroplasty--a prospective randomized double-blind placebo-controlled study

A prospective randomized double-blind placebo-controlled study was undertaken to determine the efficacy and mechanism of action of two antifibrinolytic drugs aprotinin and epsilon aminocaproic acid (EACA) in reducing blood loss in primary unilateral total hip arthroplasty (THA). Aprotinin was administered as a bolus of 2 x 10(6) kallikrein inhibitor units (KIU) followed by 0.5 x 10(6) KIU h(-1) for 3 h, EACA was given as 10 g over 30 min followed by 5 g over 3 h. The median postoperative blood loss 24 h postoperatively was reduced from 450 mL in the placebo group to 180 mL for aprotinin (60% reduction, P < 0.001) and to 210 mL for EACA (53% reduction, P < 0.01). In this population, there was no reduction in the perioperative transfusion requirements. The mechanism of both drugs was independent of platelets as indicated by flow cytometric measurement of change of their expression of P-selectin, platelet-monocyte aggregates, V/Va and CD40 ligand. There were no thrombotic or infective complications and no adverse events were attributable to use of either drug. Infusion of either aprotinin or EACA at the doses described is a safe and effective means of reducing blood loss after THA. These therapies provide a means of reducing blood loss in THA patients.

Shaken baby syndrome masquerading as apparent life threatening event

A variety of diseases and disorders can present as an acute life-threatening event among which shaken baby syndrome has been recently recognized. A high index of suspicion along with an ophthalmologic evaluation and cranial imaging helps to identify this form of child abuse, which needs multidisciplinary management.

Evaluation of the role of melatonin in formalin-induced pain response in mice

BACKGROUND

Melatonin, the major secretory product of pineal gland has been suggested to play a regulatory role in the circadian rhythm of body activities including the pain sensitivity. Three subtypes of melatonin receptors, i.e. ML1, ML2 and ML3 have been identified.

AIM

To investigate the antinociceptive activity of melatonin and to unravel the underlying receptor mechanisms involved in this action.

MATERIAL AND METHODS

Effect of melatonin (25-100 mg/kg, ip) and its interaction with putative melatonin receptor antagonists and opioidergic and serotoninergic agents have been studied in formalin test, a model of tonic continuous pain. Formalin (0.1 ml of 1% solution) was injected under the plantar surface of right hind paw of mice and the time an animal spent in licking the injected paw was measured.

STATISTICAL ANALYSIS

The data were analysed by one-way ANOVA followed by Tukey's test for multiple comparisons.

RESULTS

Injection of formalin produced two phases of intense licking, an early phase (0-5 min) and a late phase (20-25 min). Melatonin dose-dependently decreased the licking response in both the phases, effect being more marked in the late phase. Luzindole, a ML1 receptor antagonist did not block but rather enhanced the antinociceptive activity of melatonin. However, prazosin, a ML2 receptor antagonist in the low dose (0.5 mg/kg) significantly attenuated but in higher dose (1 mg/kg) enhanced the analgesic effect of melatonin. Naloxone, an opioid receptor antagonist did not reverse but morphine, an opioid agonist enhanced the antinociceptive activity of melatonin. Both mianserin and ondansetron the 5HT2 and 5HT3 receptor antagonists, respectively increased the analgesic effect of melatonin.

CONCLUSION

The present results suggest the involvement of ML2 receptors in mediating the antinociceptive activity of melatonin in formalin-induced pain response. Further an interplay between melatonin, alpha-1 adrenergic and 5HT2 and 5HT3 serotoninergic receptors may also be participating in this action.

Receptor mechanisms involved in the anticonvulsant effect of melatonin in maximal electroshock seizures

The present study investigates the mechanisms involved in the anticonvulsant effect of melatonin in maximum electroshock (MES) seizures. Melatonin (25-100 mg/kg) dose-dependently decreased the duration of tonic hindlimb extension (THLE). The anticonvulsant effect of melatonin was blocked by bicuculline, a GABA(A) receptor antagonist, and luzindole, an ML(1) receptor antagonist, while prazosin, an ML(2) receptor antagonist, enhanced the anticonvulsant actions of melatonin in this seizure model. Administration of serotonergic agents, mianserin and ondansetron, along with melatonin, increased the antiseizurogenic activity of melatonin, while buspirone had no effect. Pretreating the animals with diazepam, carbamazepine or lamotrigine enhanced the anticonvulsant effect of melatonin. Melatonin thus appears to be an effective anticonvulsant, and melatonin ML(1) receptors, GABAergic and serotonergic mechanisms may play an important role in mediating the anticonvulsant activity of melatonin in electroshock seizures.

Reversible brain lesions in childhood hypertension

Posterior leukoencephalopathy syndrome is characterized by an acute, usually reversible, encephalopathy with transient occipital lobe abnormalities detected on MRI that occur mostly in association with acute hypertension. The clinical presentation includes seizures, headache, altered mental status and blindness. Disturbed autoregulation of cerebral blood flow and endothelial injury are central to the pathogenesis of this disorder. Prompt control of hypertension results in rapid and complete neurological recovery. In this report we discuss the cases of two children with acute onset hypertension of different aetiologies that presented with the characteristic features of posterior leukoencephalopathy syndrome.

CONCLUSION

Early recognition of this readily treatable condition may obviate the need for extensive and invasive investigations. Despite the alarming lesions on the MRI, prompt control of hypertension carries a uniformly favourable prognosis.

Trypan blue assisted phacoemulsification in corneal opacities

AIM

To evaluate the efficacy of trypan blue for enhancing visualisation during phacoemulsification and foldable lens implantation in cases of cataract with corneal opacities.

METHODS

11 eyes of 11 patients with nebulomacular corneal opacities involving the visual axis with partially and visually debilitating cataract underwent trypan blue assisted phacoemulsification with foldable intraocular lens implantation. The patients were followed at the first day, first week, first month, and third month postoperatively. Completion of capsulorhexis, phacoemulsification with foldable lens implantation, and postoperative best corrected visual acuity were measured.

RESULTS

The dye improved visualisation of the anterior capsule and a complete capsulorhexis could be performed successfully in all eyes. In all but one eye phacoemulsification was accomplished successfully. In one eye with Fuchs' dystrophy penetrating keratoplasty was performed later. Visual acuity was < or = 6/60 preoperatively in all eyes and improved to > or = 6/24 in eight eyes postoperatively.

CONCLUSION

Trypan blue assisted phacoemulsification may be performed in selected cases of corneal haze/opacification with cataract. It provides acceptable visual outcome in cases awaiting penetrating keratoplasty or in cases where it is not feasible or promising.

Apoptotic changes in cervical intraepithelial neoplasia

We examined apoptosis in paraffin-embedded archival cervical tissues from cervical intraepithelial neoplasia (CIN) cases to determine whether the apoptotic process is involved in the cellular changes of CIN. Apoptotic bodies, determined by the Tunel method, were largely found at the surface epithelium in a few tissue specimens with no significant abnormality and in most tissues with CIN. Apoptotic bodies were also found within the stratified epithelium of CIN lesions and were altogether absent in specimens with no significant abnormalities. The apoptotic index was significantly associated with the severity of CIN and not with either age or human papillomavirus infection. Based on the findings of increased numbers of apoptotic bodies and their presence within the stratified epithelium in CIN tissues, we hypothesize that dysregulation in the exfoliation of apoptotic cells and resistance towards apoptosis may be prerequisites for the pathogenesis of CIN.

Identification of a critical lysine residue at the active site in glyceraldehyde-3-phosphate dehydrogenase of Ehrlich ascites carcinoma cell. Comparison with the rabbit muscle enzyme

The involvement of the lysine residue present at the active site of Ehrlich ascites carcinoma (EAC) cell glyceraldehyde-3-phosphate dehydrogenase (Gra3PDH) was investigated by using the lysine specific reagents trinitrobenzenesulfonic acid (TNBS) and pyridoxal phosphate (PP). Both TNBS and PP inactivated EAC cell Gra3PDH with pseudo-first-order kinetics with the rate dependent on modifier concentration. Kinetic analysis, including a Tsou plot, indicated that both TNBS and PP apparently react with one lysine residue per enzyme molecule. Two of the substrates, d-glyceraldehyde-3-phosphate and NAD, and also NADH, the product and competitive inhibitor, almost completely protected the enzyme from inactivation by TNBS. A comparative study of Gra3PDH of EAC cell and rabbit muscle indicates that the nature of active site of the enzyme is significantly different in these two cells. A double inhibition study using 5,5'-dithiobis(2-nitrobenzoic acid) and TNBS and subsequent reactivation of only the rabbit muscle enzyme by dithiothreitol suggested that a cysteine residue of this enzyme possibly reacts with TNBS. These studies on the other hand, confirm that an essential lysine residue is involved in the catalytic activity of the EAC cell enzyme. This difference in the nature of the active site of EAC cell Gra3PDH that may be related to the high glycolysis of malignant cells has been discussed.

Antinociceptive activity of a neurosteroid tetrahydrodeoxycorticosterone (5alpha-pregnan-3alpha-21-diol-20-one) and its possible mechanism(s) of action

The present study investigates the effects of a neurosteroid tetrahydrodeoxycorticosterone (5alpha-pregnan-3alpha-21-diol-20-one) in two experimental models of pain sensitivity in mice. Tetrahydrodeoxycorticosterone (2.5, 5 mg/kg, i.p.) dose dependently decreased the licking response in formalin test and increased the tail flick latency (TFL) in tail flick test. Bicuculline (2 mg/kg, i.p.), a GABA(A) receptor antagonist blocked the antinociceptive effect of tetrahydrodeoxycorticosterone in TFL test but failed to modulate licking response in formalin test. Naloxone (1 mg/kg, i.p.), an opioid antagonist effectively attenuated the analgesic effect of tetrahydrodeoxycorticosterone in both the models. Tetrahydrodeoxycorticosterone pretreatment potentiated the antinociceptive response of morphine, an opioid compound and nimodipine, a calcium channel blocker in formalin as well as TFL test. Thus, tetrahydrodeoxycorticosterone exerts an analgesic effect, which may be mediated by modulating GABA-ergic and/or opioid-ergic mechanisms and voltage-gated calcium channels.

Oversized corneal grafts for corneal opacities with iridocorneal adhesions

OBJECTIVE

To evaluate the efficacy of 1-mm oversized corneal grafts in patients with acquired corneal opacities and extensive peripheral iridocorneal adhesions.

DESIGN

Prospective noncomparative case series.

PARTICIPANTS

Twenty patients (20 eyes) aged 15 years or older with unilateral or bilateral corneal opacification and a shallow anterior chamber.

INTERVENTION

Penetrating keratoplasty was performed with donor corneal buttons oversized by 1 mm.

MAIN OUTCOME MEASURES

The various parameters evaluated were visual acuity, graft clarity, keratometry, anterior chamber depth, intraocular pressure, and spherical equivalent refraction 12 months after surgery.

RESULTS

The keratoplasties were performed in 15 eyes with a corneo-iridic scar after infectious keratitis (75%) and 5 eyes with failed graft (25%). At the final follow-up, a clear graft was achieved in 17 eyes (85%), and 14 eyes (70%) achieved a best-corrected visual acuity of 6/12 or better. Three of the grafts failed because of rejection. The average keratometry was 44.1 +/- 1.0 diopters (D), and the mean spherical equivalent was -3.23 +/- 2.86 D. The oversized grafts provided a mean anterior chamber depth of 2.36 +/- 0.42 mm, and the mean intraocular pressure at the 12 month follow-up was 16.38 +/- 2.09 mmHg.

CONCLUSIONS

Corneal grafts oversized by 1 mm provide adequate anterior chamber depth and reduce the risk of peripheral anterior synechiae and secondary glaucoma in patients with corneal opacities and extensive peripheral iridocorneal adhesions.