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Biomedical subjects

Adam Smith

Publications and source records attributed to Adam Smith.

13 recordsLinked to original sources
PubMed2005

Genetically induced retinal degeneration leads to changes in metabotropic glutamate receptor expression.

In the retina, neurotransmission from photoreceptors to ON-cone and rod bipolar cells is sign reversing and mediated by the metabotropic glutamate receptor mGluR6, which converts the light-evoked hyperpolarization of the photoreceptors into depolarization of ON bipolar cells. The Royal College of Surgeons (RCS) rat retina undergoes progressive photoreceptor loss due to a genetic defect in the pigment epithelium cells. The consequences of photoreceptor loss and the concomitant loss of glutamatergic input to second-order retinal neurons on the expression of the metabotropic glutamate receptor was investigated in the RCS rat retina from early stages of photoreceptor degeneration (P17) up to several months after complete rod and cone degeneration (P120). The expression of the gene encoding mGluR6 was studied by in situ hybridization in the retina, using an [(35)S]dATP-labeled oligonucleotide probe. In congenic control and RCS retina, we found mRNA expression of mGluR6 receptor only in the outer half of the inner nuclear layer (INL) on emulsion-coated retinal sections. Quantitative analysis of the hybridization signal obtained from the autoradiographic films revealed decreased expression levels of the mGluR6 mRNA at early stages of photoreceptor degeneration (P17). On the contrary, increased expression levels were observed at late stages of degeneration (P60 and P120) in RCS compared to congenic control retina. In conclusion, our data demonstrate that the metabotropic glutamate receptor-6 mRNA levels are altered in the young and adult RCS rat retina and suggest that the genetically induced degeneration of photoreceptors affects the expression of this receptor by the INL retinal neurons.

Age Factors↗
PubMed2005

Epidermoid cyst of the sphenoid sinus with extension into the sella turcica presenting as pituitary apoplexy: case report.

BACKGROUND: Epidermoids of the central nervous system are rare tumors. They are usually found in the fourth decade of life and most commonly off midline in the cerebellopontine angle. We report here a rare case of an epidermoid arising from the sphenoid sinus with extension into the sella and adjacent structures with acute onset of neurological deficit. The significance of the clinical presentation resembling pituitary apoplexy and magnetic resonance imaging (MRI) findings is noted. CASE DESCRIPTION: A 25-year-old man presented with acute severe headache, diplopia, and decreased visual acuity. Examination revealed right-sided ptosis and paresis of the third cranial nerve on the right side. Computed tomography and MRI were suggestive of a slow-growing sphenoid sinus mass with extension into the sella. The sublabial transsphenoidal approach was used to remove the mass under direct visualization. The patient's neurological status improved to baseline both subjectively and objectively after the operation. CONCLUSION: Epidermoids, although rare, should be considered as part of the differential diagnosis when evaluating lesions of sphenoid sinus or sellar origin.

Acute Disease↗
PubMed2005

Characterization of a novel porin protein from Moraxella catarrhalis and identification of an immunodominant surface loop.

Moraxella catarrhalis is a gram-negative bacterium that is mainly responsible for respiratory tract infections. In this study we report a novel outer membrane protein (OMP), designated M35, with a molecular mass of 36.1 kDa. This protein was structurally homologous to classic gram-negative porins, such as OMP C from Escherichia coli and OMP K36 from Klebsiella pneumoniae, with a predicted structure of 8 surface loops and 16 antiparallel beta-sheets. The DNA sequences of the genes from 18 diverse clinical isolates showed that the gene was highly conserved (99.6 to 100% of nucleotides), with only one isolate (ID78LN266) having base variations that resulted in amino acid substitutions. Electrophoresis and analysis of recognition of the protein using mouse anti-M35 sera showed that M35 was expressed on the bacterial surface and constitutively expressed across M. catarrhalis isolates, with only ID78LN266 showing poor antibody recognition. Our results showed that the single amino acid mutation in loop 3 significantly affected antibody recognition, indicating that loop 3 appeared to contain an immunodominant B-cell epitope. The antibody specificity to loop 3 may be a potential mechanism for evasion of host immune responses targeted to M35, since loop 3 should theoretically orientate into the porin channel. Thus, M35 is a highly conserved, surface-expressed protein that is of significance for its potential functional role as an M. catarrhalis porin and is of interest as a vaccine candidate.

Bacterial Outer Membrane Proteins↗
PubMed2004

Umbilical and bilateral inguinal hernias in a veteran powerlifter: is it a pressure-overload syndrome?

Umbilical, inguinal and hiatal hernias are all thought to occur from basically the same etiology, a malformation in the tissue leading to herniation. The mechanisms for these malformations range from congenital to degenerative. Earlier studies proposed that hiatal hernias result from age-related degenerative changes in the phrenoesophageal ligament leading to subsequent herniation. We found that hiatal hernias occur in young power athletes secondary to intra-abdominal pressure overload of the phrenoesophageal ligament. We present a case of umbilical and bilateral inguinal hernias occurring in a veteran powerlifter. The pathogenesis of multiple hernias and the physiological pressure systems involved in the development of multiple hernias in a power athlete are discussed.

Adult↗
PubMed2004

A pilot study of functional magnetic resonance imaging brain correlates of deception in healthy young men.

We hypothesized that specific brain regions would activate during deception, and these areas would correlate with changes in electrodermal activity (EDA). Eight men were asked to find money hidden under various objects. While functional MRI images were acquired and EDA was recorded, the subjects gave both truthful and deceptive answers regarding the money's location. The group analysis revealed significant activation during deception in the orbitofrontal cortex (OFCx) and anterior cingulate (AC), but individual results were not consistent. Individually and as a group, EDA correlated with blood flow changes in the OFCx and AC. Specific brain regions were activated during deception, but the present technique lacks good predictive power for individuals.

Adolescent↗
PubMed2002

Renal abnormalities in beckwith-wiedemann syndrome are associated with 11p15.5 uniparental disomy.

Beckwith-Wiedemann syndrome (BWS) is a somatic overgrowth syndrome characterized by a variable incidence of congenital anomalies, including hemihyperplasia and renal malformations. BWS is associated with disruption of genomic imprinting and/or mutations in one or more genes encoded on 11p15.5, including CDKN1C (p57(KIP2)). It was hypothesized that genotypic and epigenotypic abnormalities of the 11p15.5 region affecting CDKN1C were associated with renal abnormalities. Medical records for 159 individuals with BWS were reviewed. All underwent at least one abdominal ultrasonographic evaluation. Testing for paternal uniparental disomy (UPD) at 11p15.5, CDKN1C mutations, and imprinting defects at KvDMR1 was performed for 96, 32, and 47 patients, respectively. Of the 159 patients, 67 (42%) exhibited renal abnormalities, mainly nephromegaly (25%), collecting system abnormalities (11%), and renal cysts (10.5%). The frequency of renal lesions among patients who were tested for genetic abnormalities did not differ from that among patients who were not tested. Paternal UPD was demonstrated in 22 of 96 cases (23%), CDKN1C mutations in eight of 32 cases (25%), and KvDMR1 imprinting defects in 21 of 47 cases (45%). The 22 UPD-positive patients exhibited a significantly higher incidence of renal abnormalities (P = 0.0026). Surprisingly, the eight patients with CDKN1C mutations exhibited no significant increase in the incidence of renal lesions (P = 0.29). Imprinting defects at KvDMR1, which might downregulate CDKN1C, were also not associated with a significant difference in the incidence of renal disease. Whereas UPD at 11p15.5 in BWS was associated with a higher incidence of renal abnormalities, mutations at CDKN1C and KvDMR1 imprinting defects were not, suggesting that imprinted genes on 11p15.5 other than CDKN1C are critical for renal development.

Adolescent↗