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Biomedical subjects

P Mittal

Publications and source records attributed to P Mittal.

16 recordsLinked to original sources
PubMed1996

Posterior occipitoaxial fusion for atlantoaxial dislocation associated with occipitalized atlas.

Between 1989 and 1994, 50 patients suffering from congenital atlantoaxial dislocation with either an assimilated atlas or a thin or deficient posterior arch of the atlas were treated with occipitocervical fusion using the technique described by Jain and colleagues in 1993 with a few modifications. An artificial bridge created from the occipital bone along the margin of the foramen magnum was fused to the axis using sublaminar wiring and interposed strut and lateral onlay bone grafts. Ten patients (20%) also underwent atlantoaxial lateral joint fusion by intraarticular instillation of bone chips. In 22 patients (44%) with irreducible dislocation, posterior fusion was preceded by transoral odontoidectomy. In seven patients (14%) with ventral compression, who showed marked clinical improvement on traction despite radiological evidence of persisting atlantoaxial dislocation, occipitocervical fusion was performed without ventral decompression. Seven patients (14%) underwent a single-stage transoral odontoidectomy and posterior fusion. There was no perioperative mortality and the osseous fusion rate was 88%. Of the 43 patients available at follow-up examination (range 3-12 months), 31 patients (72.09%) improved, seven (16.28%) remained the same, and five (11.6%) deteriorated in comparison with their preoperative status. Hence, this technique achieves a stable occipitocervical arthrodesis without supplemental external orthoses and facilitates early postoperative mobilization.

Adolescent↗
PubMed1994

Gliosarcomas: pathological spectrum.

Pathological spectrum as seen in sixteen cases of gliosarcomas out of 81 cases of glioblastomas is described. Temporal lobe involvement (37.5%) and fibrosarcomatous pattern (62.5%) were found to be most frequent. Osteochondromatous element was found in recurrence of one gliosarcoma. Minimal criteria for diagnosis, pitfalls in diagnosis, differential diagnosis and histogenesis of gliosarcoma are discussed.

Adolescent↗
PubMed1993

Mouse MHC class I-like Fc receptor encoded outside the MHC.

In many mammalian species antibodies transmitted from the mother provide humoral immunity to the young. Maternal IgG from milk is transported across the intestinal epithelium of neonatal rats by an Fc receptor (FcRn) that comprises an alpha-chain similar to the class I Ag of the MHC and beta 2-microglobulin. Suckling mice also acquire antibodies by uptake from the gut. We made a neonatal mouse intestinal cDNA library and screened it with a probe encoding rat FcRn alpha-chain. The nucleotide and predicted amino acid sequences of the two positive clones were very similar to those of rat FcRn. Comparison of the FcRn domains to various MHC class I and CD1 molecules suggests a divergence of FcRn from MHC early in the mammalian lineage. We expressed one of these cDNA in mouse 3T3 fibroblasts. Cells that expressed the cDNA product bound the Fc fragment of IgG with the same pH dependence as neonatal rat intestinal epithelium. We detected RNA that hybridize with the mouse cDNA only in neonatal small intestine and fetal yolk sac, two tissues involved in IgG transport. These data show that the mouse cDNA code for FcRn alpha-chain. The mouse FcRn alpha-chain is similar in sequence to the class I MHC Ag, encoded on chromosome 17 in the mouse. However, we find that the mouse FcRn gene lies outside the MHC, on chromosome 7.

Amino Acid Sequence↗
PubMed1993

"Z" flow hydrocephalus shunt, a new approach to the problem of hydrocephalus, the rationale behind its design and the initial results of pressure monitoring after "Z" flow shunt implantation.

The over-drainage of CSF after shunt implantation, particularly when the patient is in the vertical posture, is well documented. Problems associated with it are negative pressure syndrome (postural headache and postural irritability), abnormal skull size, craniosynostosis and subdural haematoma. The pressure gradient in the vertical position between the cranial cavity and the right atrium is 15 to 20 cm of water and between the cranial and peritoneal cavity it is 25 to 32 cm of water and both these are much higher than those needed for the optimum functioning of a conventional shunt. The need, therefore, has been for a self-regulating device that can adjust itself to any change of posture from horizontal to vertical and vice versa and regulate the flow of CSF from the cranial cavity. "Z" Flow hydrocephalus shunt system has this in-built self-regulating mechanism to prevent over drainage of CSF and the resultant abnormal low pressure in the cranial cavity. The rationale behind the functioning of "Z" Flow hydrocephalus shunt system has been discussed, its design has been described and illustrated and the results of pressure monitoring after Z Flow shunt implantation in five adult patients have been detailed. As the opening pressures of the "Z" Flow shunt system are 15-29 cm of water, it has been found to prevent over-drainage of CSF and maintain intraventricular pressure within normal limits.

Adult↗
PubMed1993

Intracranial tuberculomas: MRI signal intensity correlation with histopathology and localised proton spectroscopy.

In seven cases of intracranial tuberculomas showing different signal intensities on MRI (five characteristic and two nonspecific), detailed histopathological examination was performed to look for number of macrophages, fibrosis, gliosis, degree of inflammatory cellular infiltrate, and type of caseation. The granulomas showing more macrophages, fibrosis and gliosis appeared hypointense on T2-weighted images. Tuberculomas showing minimal macrophages, marked cellular infiltration, and minimal fibrosis appeared hyperintense on T2-weighted images. Lesions showing similar signal intensity on T2-weighted images showed variation in the amount of macrophages, cellular infiltrates, maturity and fibrosis. Trace element estimation was done (iron, copper, and magnesium) in two of these lesions appearing hypointense on T2 and two normal brain samples; these were significantly lower in tuberculoma compared to normal brain tissue. Localised proton spectroscopy was performed in two hypointense lesions which showed marked increase in peaks in the region of mobile lipids (1.28 ppm) compared to normal brain parenchyma. It is concluded that the signal intensity of the lesions is dependent on the number of macrophages, fibrosis and cellular infiltrates. In addition increased lipid contents in the tuberculoma also contribute to the hypointensity on T2-weighted images.

Adult↗
PubMed1993

Signal intensity patterns in intraspinal dermoids and epidermoids on MR imaging.

Retrospective evaluation of MR images of nine intraspinal dermoid (n = 4) and epidermoid (n = 5) tumours was undertaken. T1-weighted images were available in all the patients while proton density (PD) and T2-weighted images were available in seven patients. Except for one lesion (only T1-weighted images were available in this case), all the lesions were clearly delineated on MR images. Most (5 out of 7) were better appreciated on T1- and PD-weighted images than on T2-weighted images. On T1-weighted images, the epidermoids were either iso- to mildly hypointense to the cord (n = 3), isointense to CSF (n = 1) or markedly hyperintense (n = 1). On the PD images, the epidermoids were either isointense to cord (n = 3) or markedly hyperintense (n = 1). All the lesions were iso- to hyperintense to CSF on T2-weighted images. Of the four dermoids three showed a mixed intensity pattern on all sequences; the dominant component gave short T1 and short T2 values, consistent with fat. The fourth lesion showed homogenous material with a signal intensity intermediate between that of CSF and cord on T1-weighted images. Dermal sinus tracts were present in four of the nine patients; three patients had an intraspinal component. This study shows that although MR imaging is excellent for their detection, it cannot differentiate the two tumour types.

Cerebrospinal Fluid↗
PubMed1992

A simplified technique for lengthening peritoneal catheters.

Existing techniques for lengthening a peritoneal catheter require a formal laparotomy, and exploration for the catheter which is then extended by the addition of a necessary length. We describe a simplified technique which is quicker and which in co-operative patients can be done under local anaesthesia on an out-patient basis. In this technique the peritoneal catheter along with its fibrous sheath is dissected and after opening the sheath an additional length is added. The elongated catheter is replaced through the same tubular sheath into the peritoneal cavity.

Body Height↗
PubMed1991

A modified technique for placement of the peritoneal end of a shunt system: technical note.

Infection and extrusion of the peritoneal catheter can complicate shunt surgery. We present a modification in the technique of peritoneal catheter placement which can help reduce the incidence of these complications, as it places the peritoneal catheter away from the abdominal wound. The subcutaneous passer is first introduced into the peritoneal cavity through the abdominal incision. It is then thrust superficially and manipulated into the subcutaneous plane, from where the procedure follows the conventional steps. We have followed this technique for 6 years without any additional hazard attributed to this procedure.

Cerebrospinal Fluid Shunts↗
PubMed1990

Weight and height norms of 5-10 years old children of upper socio-economic status.

One thousand and twenty four school children (574 boys and 450 girls) between the ages of 5-10 years, belonging to upper socio-economic status were cross sectionally studied to establish regional weight and height norms. The boys were heavier till the age of 9 years while the girls were heavier than boys beyond that age. The boys were taller than the girls between 5-9 years and thereafter the girls over took the boys.

Body Height↗