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George John

Publications and source records attributed to George John.

15 recordsLinked to original sources
PubMed2006

Enzyme catalysis: tool to make and break amygdalin hydrogelators from renewable resources: a delivery model for hydrophobic drugs.

We report a novel approach for the controlled delivery of an antiinflammatory, chemopreventive drug by an enzyme-triggered drug release mechanism via the degradation of encapsulated hydrogels. The hydro- and organogelators are synthesized in high yields from renewable resources by using regioselective enzyme catalysis, and a known chemopreventive and antiinflammatory drug, i.e., curcumin, is used for the model study. The release of the drug occurred at physiological temperature, and control of the drug release rate is achieved by manipulating the enzyme concentration and/or temperature. The byproducts formed after the gel degradation were characterized and clearly demonstrated the site specificity of degradation of the gelator by enzyme catalysis. The present approach could have applications in developing cost-effective controlled drug delivery vehicles from renewable resources, with a potential impact on pharmaceutical research and molecular design and delivery strategies.

Amygdalin↗
PubMed2005

Local environment and property of water inside the hollow cylinder of a lipid nanotube.

We investigated the local environment of water confined inside the hollow cylinder of lipid nanotubes (LNTs) by time-resolved fluorescent measurements and attenuated-total-reflectance infrared (ATR-IR) spectroscopy. The LNT was obtained by self-assembly of cardanyl glucosides in water at room temperature and had an open-ended cylindrical nanospace with a diameter of 10-15 nm, a length of 10-100 microm, and hydrophilic inner and outer surfaces. We introduced a fluorescent probe of 8-anilinonaphthalene-1-sulfonate into the confined water and observed an extremely slow dynamic Stokes shift with a correlation time of 1.26 ns, which was 2-3 orders of magnitude longer than that of bulk-phase water. From the peak shift of the fluorescent spectrum, the local solvent polarity (ET(30)) of the confined water was estimated as 50 kcal/mol, which is 20% lower than that in bulk water. ATR-IR measurements showed that the hydrogen-bond network of water inside the LNT was more developed than that in bulk water at room temperature, which is in contrast to the water in other self-assembled confined geometries, such as Aerosol-OT (AOT) reversed micelles.

Anilino Naphthalenesulfonates↗
PubMed2005

An unusual scrotal lump.

Polyorchidism is a rare anomaly of the genital tract in which supernumerary testes are present, usually within the scrotum. Less than 100 cases have been reported in the literature. We present a case of polyorchidism in which the diagnosis was made on ultrasonography and as there was no evidence of an associated pathology on clinical examination or imaging, surgical exploration was therefore not considered necessary.

Adult↗
PubMed2005

Primary carcinoid tumour of the testis.

A left radical orchidectomy was performed on a 32-year-old man presenting with a testicular mass. Histology revealed a tumour comprising of cells with monotonous nuclei and granular cytoplasm arranged in an insular pattern. Immunohistochemical expression for NSE, synaptophysin and chromogranin A were positive. No teratomatous elements were seen. Postoperatively, a staging CT and an octreotide scan were normal. Urinary 5-HIAA levels were not elevated. Based on these investigations the tumour was diagnosed as a pure primary carcinoid tumour of the testis. The patient has been followed up for 3 years with no evidence of recurrence.

Adult↗
PubMed2004

Lipid-based nanotubes as functional architectures with embedded fluorescence and recognition capabilities.

A limited combinatorial strategy was used to synthesize a small library of soft lipid-based materials ranging from structurally unordered fibers to highly uniform nanotubes. The latter nanotubes are comprised of a bilayer structure with interdigitated alkyl chains associated through hydrophobic interactions. These tubes contain accessible 2,6-diaminopyridine linkers that can interact with thymidine and related nucleosides through multipoint hydrogen bonding, thereby quenching the intrinsic fluorescence of the aromatic linker. These results are the first example of a systematic strategy to design functional lipid nanotubes with precise structural and functional features.

Aminopyridines↗
PubMed2004

Unsaturation effect on gelation behavior of aryl glycolipids.

Structurally simple, renewable-resource-based cardanyl (glucoside)s [1, 1-O-3'-n-(pentadecyl) phenyl-beta-D-glucopyranoside; 2, 1-O-3'-n-(8'(Z)-pentadeceenyl)-beta-glucopyranoside; 3, 1-O-3'-n-(8'(Z),11'(Z)pentadecadienyl)phenyl-beta-D-glucopyranoside, 4; 1-O-3'-n-(8'(Z),11'(Z),14'-pentadecatrienyl)phenyl-beta-D-glucopyranoside; and the mixture 5] form thermally reversible transparent gels in a water/alcohol mixture and a number of organic solvents, strongly influenced by the unsaturation of the aliphatic alkyl chain. DSC studies revealed that the Tgel of 1 in water/ethanol (1:1, vol/vol) gel is 69.0 degrees C, while of the introduction of a single double bond reduces the value to 30.0 degrees C in the case of monoene 2, indicating that the stability of the gel is related to the number of double bonds on the lipophilic part of the gelator. Furthermore, XRD measurements showed that the aqueous gel 1 maintains an interdigitated bilayered structure with 3.14 nm long-range ordering, and the corresponding organogel maintains an extended bilayer structure for 4.34 nm, indicating a clear difference in the aggregation behavior in different solvents.

Gels↗
PubMed2002

Morphological control of helical solid bilayers in high-axial-ratio nanostructures through binary self-assembly.

Mixed molecular species of cardanyl glucoside derived from renewable resources provide nanotubes upon self-assembly in water, while the saturated homologue generated a twisted fibrous morphology. The cardanyl glucoside mixture was fractionated into four individual components in order to study their contribution to the nanotube formation. The rational control of self-assembled helical morphologies was achieved by binary self-assembling of the saturated and monoene derivatives. This method can generate a diversity of self-assembled high-axial-ratio nanostructures (HARNs), ranging from twisted ribbons and helical ribbons to nanotubes.

Calorimetry, Differential Scanning↗
PubMed2002

Self-assembling structures of long-chain phenyl glucoside influenced by the introduction of double bonds.

Four long-chain phenyl glucoside amphiphiles possessing a saturated or unsaturated long alkyl chain group as the self-assembling unit of a highly organized molecular architecture were synthesized. Their self-assembling properties were investigated by EF-TEM, SEM, CD, FT-IR, and XRD. Compound 2 possessing one double bond in the lipophilic portion showed twisted helical fibers, which formed a bilayered structure with a 3.59 nm period, while compound 3 showed the helical ribbons and left-handed nanotubular structures with 150-200 nm inner diameters and ca. 20 nm of wall. Very interestingly, compound 4 possessing three double bonds showed a nanotubular structure with ca. 70 nm of inner diameter through a helical ribbon, which formed a loose bilayered structure with 4.62 nm. These results indicate that self-assembling properties strongly depend on the number of cis double bonds.

Circular Dichroism↗
PubMedDate not supplied

Acute fatty liver of pregnancy: a report of two cases.

Acute fatty liver of pregnancy is an uncommon, potentially fatal disorder. Between 1998 and 2000, two patients with acute fatty liver of pregnancy presented at the Christian Medical College Hospital, Vellore. Both patients were in the thirty-sixth week of pregnancy. jaundice and encephalopathy were the predominant symptoms. Both the mothers died after they delivered a stillborn Infant each. The maternal deaths were due to multiorgan failure and/or postpartum haemorrhage and sepsis. The route of delivery was vaginal in both the patients. Extrahepatic and metabolic complications in both cases Included renal failure, sepsis, hypoglycaemia, disseminated intravascular coagulation and gastrointestinal bleeding. Liver biopsy done in both patients was consistent with the diagnosis of acute fatty liver of pregnancy. To the best of our knowledge, this is the first report from India on acute fatty liver of pregnancy.

Acute Disease↗