Genetics of sarcoidosis

Hereditary susceptibility to sarcoidosis is suggested by ethnic preponderance, familial clustering, and multigenerational involvement. The genetics of sarcoidosis cannot be adequately addressed in small samples of patients; a large-scale study with stratification for patient phenotypic differences is necessary. A study that uses both genetic marker and environmental data would be able to control for and examine different causative mechanisms. Until such a well-designed, comprehensive study is carried out, we are left with interesting patterns of disease in families and uncertain allelic associations.     

Analysis of amyloid deposition in a transgenic mouse model of homozygous familial amyloidotic polyneuropathy

Amyloid fibrils derived from the Japanese, Portuguese, and Swedish types of familial amyloidotic polyneuropathy all consist of a variant transthyretin (TTR) with a substitution of methionine for valine at position 30 (TTR Met 30). In an attempt to establish an animal model of TTR Met-30-associated homozygous familial amyloidotic polyneuropathy and to study the structural and functional properties of human TTR Met 30, we generated a mouse line carrying a null mutation at the endogenous ttr locus (ttr-/-) and the human mutant ttr gene (6.0-hMet 30) as a transgene. In these mice, human TTR Met-30-derived amyloid deposits were first observed in the esophagus and stomach when the mice were 11 months of age. With advancing age, amyloid deposits extended to various other tissues. Because no significant difference was detected in the onset, progression, and tissue distribution of amyloid deposition between the ttr-/- and ttr+/+ transgenic mice expressing 6.0-hMet 30, endogenous normal mouse TTR probably does not affect the deposition of human TTR Met-30-derived amyloid in mice. TTR is a tetramer composed of four identical subunits that binds thyroxine (T4) and plasma retinol-binding protein. The introduction of 6.0-hMet 30 into the ttr-/- mice significantly increased their depressed serum levels of T4 and retinol-binding protein, suggesting that human TTR Met 30 binds T4 and retinol-binding protein in vivo. The T4-binding ability of human TTR Met 30 was confirmed by the analysis of T4-binding proteins in the sera of ttr-/- transgenic mice expressing 6.0-hMet 30. The T4-binding studies also demonstrated the presence of hybrid tetramers between mouse and human TTR subunits in the ttr+/+ transgenic mice expressing 6.0-hMet 30.     

Predicting compliance with annual follow-up evaluations in persons with spinal cord injury

In this study a representative sample of German acute care hospitals is used to describe the effects of dementia within acute care hospitals. Data from hospital patients above age 60 with the diagnosis dementia (ICD 290, 293, 294 and 310), collected over an observation period of 12 years, are compared with nondemented hospital patients at the same ages. The differences in the average length of stay between demented and nondemented patients are only relatively small in German acute care hospitals. The degree of multimorbidity is higher and hospital infections are more frequent for demented patients. The main differences occur with mortality: demented inpatients of both sexes experience a hospital mortality which is about twice as high as for nondemented patients at the same ages.     

Intrinsic signals in the unique domain target p56(lck) to the plasma membrane independently of CD4

In T lymphocytes, the Src-family protein tyrosine kinase p56(lck) (Lck) is mostly associated with the cytoplasmic face of the plasma membrane. To determine how this distribution is achieved, we analyzed the location of Lck in lymphoid and in transfected nonlymphoid cells by immunofluorescence. We found that in T cells Lck was targeted correctly, independently of the cell surface proteins CD4 and CD8 with which it interacts. Similarly, in transfected NIH-3T3 fibroblasts, Lck was localized at the plasma membrane, indicating that T cell-specific proteins are not required for targeting. Some variation in subcellular distribution was observed when Lck was expressed in HeLa and MDCK cells. In these cells, Lck associated with both the plasma membrane and the Golgi apparatus, while subsequent expression of CD4 resulted in the loss of Golgi-associated staining. Together, these data indicate that Lck contains intrinsic signals for targeting to the plasma membrane. Furthermore, delivery to this site may be achieved via association with exocytic transport vesicles. A mutant Lck molecule in which the palmitoylation site at cysteine 5 was changed to lysine (LC2) localized to the plasma membrane and the Golgi region in NIH3T3 cells. However, the localization of a mutant in which the palmitoylation site at cysteine 3 was changed to serine (LC1) was indistinguishable from wild-type Lck. Chimeras composed of only the unique domain of Lck linked to either c-Src or the green fluorescent protein similarly localized to the plasma membrane of NIH-3T3 cells. Thus, the targeting of Lck appears to be determined primarily by its unique domain and may be influenced by the use of different palmitoylation sites.     

Predicting postlaryngectomy voice outcome in an era of primary tracheoesophageal fistulization: a retrospective evaluation

The aim of this study was to investigate the effect of the absence of elongate spermatids (ES) from the rat seminiferous epithelium on the quantitative secretion and synthesis of the three major Sertoli cell secretory proteins--SGP-1, SGP-2 and CP-2. Seminiferous tubules (ST) were isolated (a) from normal 28-day-old rats, in which the most mature germ cell type is the round spermatid, (b) from normal adult rats at stages IX-XIV of the spermatogenic cycle, i.e. after spermiation, or at stages I-V and VI-VIII, when ES are still attached to the Sertoli cell, and (c) at stages VI-VIII from normal adult rats and from rats treated with methoxyacetic acid (MAA) in order to specifically deplete ES at these stages. Two-dimensional SDS PAGE combined with computerized image analysis was used to analyse 35S-methionine-labelled intracellular and secreted proteins. In the case of SGP-1 and SGP-2, almost all of the protein synthesized by ST was secreted. The total amount of both SGP-1 and CP-2 secreted by unstaged ST from immature rats was significantly lower than that secreted by unstaged ST from adult rats. The total amount of SGP-1 and CP-2 secreted by adult ST at stages IX-XIV of the spermatogenic cycle also declined dramatically compared to ST at earlier stages. The proportion of the total CP-2 synthesized by ST which was secreted also declined in all situations in which ES were absent from the seminiferous epithelium. The synthesis of only SGP-2 was changed by ES depletion from ST at stages VI-VIII, which was almost doubled compared to synthesis of this protein by ST from control rats. Our results suggest strongly that the secretion of SGP-1 and SGP-2 is via the constitutive pathway, and that regulation of these two proteins by ES is at the level of protein synthesis. In contrast, the regulation of CP-2 by ES is predominantly at the level of secretion, suggesting that this protein is secreted via a regulated pathway. Our findings add to the evidence showing that ES play a major role in the regulation of Sertoli cell function.     

Cortical and hippocampal volume deficits in temporal lobe epilepsy

PURPOSE: To use quantitative magnetic resonance imaging (MRI) methods to examine the extent of volume abnormalities in the hippocampus and in extrahippocampal brain regions in localization-related epilepsy of temporal lobe origin (TLE). METHODS: Hippocampal, temporal lobe, and extratemporal lobe volumes were examined with 3-mm spin-echo coronal MRI scans in patients with unilateral TLE who were candidates for temporal lobe resection. Measures were adjusted for normal variation due to intracranial volume and age based on 72 healthy male controls. Group differences between 14 male TLE [7 left TLE (LTLE), 7 right TLE (RTLE)] patients and a subset of 49 age range-matched controls were examined with analysis of variance (ANOVA). RESULTS: As compared with controls, patients with TLE had smaller temporal lobe and frontoparietal region gray matter volumes, bilaterally, smaller temporal lobe white matter volumes bilaterally, and larger ventricular volumes. In contrast to these bilateral tissue volume deficits, hippocampal volume deficits in TLE were ipsilateral to the epileptogenic temporal lobe. CONCLUSIONS: Extrahippocampal volume abnormalities were bilateral and occurred in both temporal and extra-temporal cortical regions in TLE, whereas hippocampal deficits were related to the side of the epileptogenic focus. These data suggest that brain abnormalities in TLE are not limited to the epileptogenic region.     

Comparative effects of enteric-coated pancreatin microsphere therapy after conventional and pylorus-preserving pancreatoduodenectomy

BACKGROUND: A comparative study was performed between patients with exocrine pancreatic insufficiency after conventional pancreatoduodenectomy (Whipple's procedure) and pylorus-preserving pancreatoduodenectomy (PPPD). In these patients the pharmacodynamics of 2-mm enteric-coated pancreatin microspheres (ECPMs) and their gastric transit time in relation to that of a solid meal were investigated. The efficacy of ECPM preparations may differ after Whipple's procedure compared with PPPD, because the latter procedure does not include gastrectomy. METHODS: Gastric transit was assessed by double-isotope scintigraphy. A pancake meal was labelled with 99mTc. ECPMs were cold-labelled with 170Er and neutron activated shortly before ingestion to enable imaging with a gamma camera. Intraluminal pancreatic enzyme activity was assessed during a 6-h period with two indirect tests: the cholesteryl [14C]octanoate breath test and the N-benzoyl-L-tyrosyl-p-aminobenzoic acid-p-aminosalicylic acid (NBT-PABA-PAS) test. RESULTS: In patients who had Whipple's procedure, the gastric transit time of ECPMs and of the pancake meal was not significantly different. The outcome of the indirect pancreatic function tests during enzyme supplementation was comparable, and not significantly different, from that in healthy volunteers. In patients who had PPPD, however, the gastric transit time of microspheres was greatly delayed compared with that of the pancake meal (P < 0.05). Improvement in the outcome of the indirect pancreatic function tests during enzyme supplementation was much less and remained well below that of healthy volunteers (P < 0.05). CONCLUSION: In cases of exocrine pancreatic insufficiency after Whipple's procedure, 2-mm ECPM treatment adequately restores pancreatic enzyme activity. Following PPPD, however, ECPM treatment is often ineffective because the microspheres are retained in the stomach. In these patients, use of conventional powdered pancreatin enzyme preparations may improve the efficacy of treatment.     

Acquisition of native beta-strand topology during the rapid collapse phase of protein folding

The 98 residue C-terminal domain of the cell-surface receptor protein CD2 (CD2.D1) has a beta-sandwich fold belonging to the immunoglobulin superfamily but lacking the usual disulfide bridges. Kinetic studies on the folding/unfolding of CD2.D1 reveal that folding proceeds through a rapidly formed intermediate state [Parker, M. J., & Clarke, A. R. (1997) Biochemistry 36, 5786-5794]. To characterize the structural properties of this intermediate we have performed a series of amide hydrogen exchange studies using the pH competition method, in which folding and exchange are initiated simultaneously. The complex beta-sheet topology of this molecule makes it an ideal object for examining the acquisition of backbone hydrogen bonds made between sequence-local and sequence-distant segments of the chain during folding. The pattern of protected amides in the intermediate reveal that the essential features of the beta-sheet topology of CD2.D1 are defined early in the folding pathway, before the development of intimate side chain interactions characteristic of the native state. The results are discussed in light of current issues concerning the mechanistic relevance of kinetic protein folding intermediates.