Caspase-3 cleaved spectrin colocalizes with neurofilament-immunoreactive neurons in Alzheimer's disease.

Corticocortical disconnection in Alzheimer's disease occurs by the progressive impairment and eventual loss of a small subset of pyramidal neurons in layers III and V of association areas of the neocortex. These neurons exhibit large somatic size, extensive dendritic arborization and high levels of nonphosphorylated neurofilaments of medium and high molecular weight that can be identified using a monoclonal SMI-32 antibody. It is thought that the accumulation of amyloid Abeta and neurofibrillary tangles may provoke metabolic disturbances that result in the loss of these SMI-32 immunoreactive neurons. The recent detection of increased levels of caspase-3 cleaved fodrin in frontal, temporal and parietal association areas in Alzheimer's disease brains suggests that programmed cell death may contribute to the destruction of SMI-32 positive neurons. In the present study, we utilized an antibody that selectively recognizes the 120 kDa breakdown product of alphaIIspectrin (fodrin) generated by caspase-3 to determine whether this protease is activated in vulnerable pyramidal neurons located in layers III and V of Alzheimer's disease brains. Neurons immunoreactive for caspase-3 cleaved alphaIIspectrin were located predominantly in layers III and V of the inferior frontal and superior temporal cortices of patients with Alzheimer's disease but not age-matched controls. Pyramidal neurons immunoreactive for caspase-3 cleaved alphaIIspectrin invariably displayed SMI-32 immunoreactivity suggesting that caspase-3 activation is a pathological event that may be responsible for the loss of a subset of pyramidal neurons that comprise corticocortical projections.

Chiropractic biophysics lateral cervical film analysis reliability.

OBJECTIVE: To determine the degree to which the geometric line drawings used in Chiropractic Biophysics Technique (CBP) on lateral cervical radiographs are reliable. DESIGN: A blind, delayed repeated measures design was used. Three examiners were presented radiographs in random order. All identifying marks were removed prior to each examiner's individual marking and measurement. Each examiner was blinded as to how the previous examiners marked and measured the radiographs. SETTING: Primary care private chiropractic clinic. PARTICIPANTS: Sixty-five subject films were provided from the patient records of a primary care private chiropractic clinic. The 65 radiographs qualified for inclusion in the study based on two criteria: C1 through C7 had to be clearly visible, and there had to be no identifying artifacts. MAIN OUTCOME MEASURES: Anterior head translation in millimeters, atlas plane to horizontal, Ruth Jackson's cervical stress lines, and five relative rotation angles for C2-C3, C3-C4, C4-C5, C5-C6, C6-C7. Inter- and intrareliability of the three examiners were statistically analyzed. RESULTS: Intraexaminer for a) C1 to horizontal reliability was .98-.99 with confidence intervals of .96-.99, b) absolute rotation angle from C2 to C7 reliability was .82-.95 with confidence intervals of .80-.99, c) anterior head translation [+Sz] reliability was .86-.99, with confidence intervals of .74-.99, d) relative rotation angle reliability ranges were (C2-C3) .99, and (C3-C4) .98-.99, (C4-C5) .88-.99, (C5-C6) .80-.99, and (C6-C7) .94-.98. Interexaminer reliabilities across examiners ranged from a) Winer:.89-.99 and b) Bartko: .72-.96. CONCLUSIONS: The reliabilities for intra- and interexaminer were all greater than .70, indicating that these measurements in CBP technique would be considered accurate enough to provide measurements for future clinical studies. The data indicated that the C6-C7 relative rotation angle was the least reliable measurement. This might be due to the very small angles found at this level.

Nitrification and nitrogen mineralization in a lowland rainforest succession in Costa Rica, Central America.

Nitrogen availability is a critical component of productivity in successional lowland rainforests, and nitrogen losses from a given system may largely depend on rates of nitrification in soils of the system. Two hypotheses were tested in a study of a 6-point secondary rainforest sere in the coastal lowlands of Costa Rica: that nitrification and N mineralization change in a directed fashion in lowland rainforest successions, and that nitrification is regulated by ammonium availability at all points along the sere. Nitrate and mineral N production were measured in short-term laboratory incubations of soils from different stages of secondary succession corresponding to 0, 3, 8, 16, 31 and 60 + years following disturbance. Results indicate that nitrification increases through the first 4 successional stages and then declines somewhat before leveling off. In soil from all sites, most of the N mineralized was nitrified, and added NH4Cl strikingly stimulated net nitrate production. Added NaH2PO4, CaCO3, and CaSO4 did not stimulate net nitrate production or did not result in a greater proportion of nitrate than in controls. These results suggest that nitrification and N mineralization may tend to increase through secondary rainforest succession and that ammonium availability along the sere regulates rates of nitrification.

Chronic hypernatremia from a congenital defect in osmoregulation of thirst and vasopressin.

An infant with microcephaly and delayed development was found to have chronic asymptomatic hypernatremia. Computerized brain tomography disclosed dysplasia of the midline structures, septum pellucidum and corpus collosum. Evaluation revealed defective osmoregulation, hypothalamic hypothyroidism, and hypogonadotropinism. He showed no desire to drink at plasma osmolalities over 330 mOsm/kg. His plasma vasopressin levels (less than or equal to 1.4 pg/ml) were inappropriately low relative to his high levels of plasma osmolality (greater than or equal to 310 mOsm/kg), which might be accounted for by either deficient neurohypophyseal vasopressin stores or disturbance of the hypothalamic osmoreceptors governing vasopressin. The first possibility was ruled out by demonstrating normal vasopressin response (167 pg/ml) to nonosmotic (emetic) stimulation. Under baseline conditions, his urine was concentrated up to 747 mOsm/kg and urine volume was low. With water loading, maximal water diuresis developed (urine osmolality 68 mOsm/kg), but his plasma osmolality remained in the hyperosmolar range (312 mOsm/kg). Treatment with a vasopressin analogue, desamino-D-arginine vasopressin, and forced hydration restored plasma osmolality and plasma sodium to normal. These findings indicate a severe defect in the hypothalamic osmoreceptors controlling thirst and vasopressin secretion with normal vasopressin stores and preserved vasopressin responsiveness to nonosmotic stimuli. To our knowledge, this report provides the first documentation of selective osmoreceptor defect in conjunction with congenital dysplasia of midline brain structures.

Radioimmunoassay of vasopressin in familial cental diabetes insipidus.

We examined plasma arginine-vasopressin concentrations by radioimmunoassay in two brothers, aged 6 and 7.5 years, with familial central diabetes insipidus inherited as an autosomal dominant trait. Plasma AVP was measured in relation to increasing plasma osmolality induced by water deprivation and hypertonic saline infusion. The brother with the more severe urinary concentrating defect had no detectable AVP when his plasma osmolality was as high as 306 mOsm/kg; the other brother had detectable but clearly subnormal AVP concentrations. The one brother tested had an apparently normal end-organ response to exogenous vasopressin. Chlorpropamide had a significant antidiuretic effect in the brother with detectable AVP levels, and a lesser effect in the other brother . Our findings suggest that intrafamilial variation in the severity of congenital DI is related to the degree of vasopressin deficiency.