Twenty-Four-Hour Variations in the Sensitivity of Rat Aorta to Vasoactive Agents

The presence of time-dependent variations in the in vitro sensitivity of aorta preparations to either vasoconstricting or relaxing agents was investigated in rats maintained in light from 08: 00 to 20: 00 and in darkness from 20: 00 to 08: 00. Rat thoracic aorta rings were obtained from animals sacrificed at four different times of the day. The rat aorta was found to be more sensitive to the constricting effect of phenylephrine at 15: 00, and of 5-hydroxytryptamine at 21: 00. On the other hand, both endothelium-dependent and -independent relaxations were more remarkable at 03: 00 than at other times of the day. These variations represented significant circadian rhythms when analyzed by analysis of variance. Different in vitro responsiveness to these agents might reflect changes in the sensitivity and/or number of related receptors in vascular preparations. In conclusion, the circadian time of animal sacrifice to obtain vascular preparations constitutes an important aspect of the research method and a key determinant of findings. (Chronobiology International, 13(6), 465-475, 1996)     

Alterations of Red Cell Membrane Properties in Nneuroacanthocytosis

Neuroacanthocytosis (NA) refers to a group of heterogenous, rare genetic disorders, namely chorea acanthocytosis (ChAc), McLeod syndrome (MLS), Huntington’s disease-like 2 (HDL2) and pantothenate kinase associated neurodegeneration (PKAN), that mainly affect the basal ganglia and are associated with similar neurological symptoms. PKAN is also assigned to a group of rare neurodegenerative diseases, known as NBIA (neurodegeneration with brain iron accumulation), associated with iron accumulation in the basal ganglia and progressive movement disorder. Acanthocytosis, the occurrence of misshaped erythrocytes with thorny protrusions, is frequently observed in ChAc and MLS patients but less prevalent in PKAN (about 10%) and HDL2 patients. The pathological factors that lead to the formation of the acanthocytic red blood cell shape are currently unknown. The aim of this study was to determine whether NA/NBIA acanthocytes differ in their functionality from normal erythrocytes. Several flow-cytometry-based assays were applied to test the physiological responses of the plasma membrane, namely drug-induced endocytosis, phosphatidylserine exposure and calcium uptake upon treatment with lysophosphatidic acid. ChAc red cell samples clearly showed a reduced response in drug-induced endovesiculation, lysophosphatidic acid-induced phosphatidylserine exposure, and calcium uptake. Impaired responses were also observed in acanthocyte-positive NBIA (PKAN) red cells but not in patient cells without shape abnormalities. These data suggest an “acanthocytic state” of the red cell where alterations in functional and interdependent membrane properties arise together with an acanthocytic cell shape. Further elucidation of the aberrant molecular mechanisms that cause this acanthocytic state may possibly help to evaluate the pathological pathways leading to neurodegeneration.     

Association of nicotinamide-N-methyltransferase (NNMT) gene rs694539 variant with bipolar disorder

Here we report the association of the rs694539 variant of nicotinamide-N-methyltransferase gene with bipolar disorder in a case–control study of 95 bipolar disorder patients and 201 healthy controls (χ² = 13.382, P = 0.001). With the polymerase chain reaction restriction fragment length polymorphism method we developed we were able to show the association for the first time. This new finding may provide evidence to understand the mechanism of the disease.     

Facile synthesis and characterization of novel pyrazole-sulfonamides and their inhibition effects on human carbonic anhydrase isoenzymes

In the current study, a series of pyrazole-sulfonamide derivatives (2–14) were synthesized, characterized, and the inhibition effects of the derivatives on human carbonic anhydrases (hCA I and hCA II) were investigated as in vitro. Structures of these sulfonamides were confirmed by FT-IR, ¹H NMR, ¹³C NMR and LC–MS analysis. ¹H NMR and ¹³C NMR revealed the tautomeric structures. hCA I and hCA II isozymes were purified from human erythrocytes and inhibitory effects of newly synthesized sulfonamides on esterase activities of these isoenzymes have been studied. The K_i values of compounds were 0.062–1.278 μM for hCA I and 0.012–0.379 μM for hCA II. The inhibition effects of 7 for hCA I and 4 for hCA II isozymes were almost in nanomolar concentration range.     

Function and regulation of tau conformations in the development and treatment of traumatic brain injury and neurodegeneration

One of the two common hallmark lesions of Alzheimer’s disease (AD) brains is neurofibrillary tangles (NFTs), which are composed of hyperphosphorylated tau protein (p-tau). NFTs are also a defining feature of other neurodegenerative disorders and have recently been identified in the brains of patients suffering from chronic traumatic encephalopathy (CTE). However, NFTs are not normally observed in traumatic brain injury (TBI) until months or years after injury. This raises the question of whether NFTs are a cause or a consequence of long-term neurodegeneration following TBI. Two conformations of phosphorylated tau, cis p-tau and trans p-tau, which are regulated by the peptidyl-prolyl isomerase Pin1, have been previously identified. By generating a polyclonal and monoclonal antibody (Ab) pair capable of distinguishing between cis and trans isoforms of p-tau (cis p-tau and trans p-tau, respectively), cis p-tau was identified as a precursor of tau pathology and an early driver of neurodegeneration in AD, TBI and CTE. Histological studies shows the appearance of robust cis p-tau in the early stages of human mild cognitive impairment (MCI), AD and CTE brains, as well as after sport- and military-related TBI. Notably, cis p-tau appears within hours after closed head injury and long before other known pathogenic p-tau conformations including oligomers, pre-fibrillary tangles and NFTs. Importantly, cis p-tau monoclonal antibody treatment not only eliminates cis p-tau induction and tau pathology, but also restores many neuropathological and functional outcome in TBI mouse models. Thus, cis p-tau is an early driver of tau pathology in TBI and CTE and detection of cis p-tau in human bodily fluids could potentially provide new diagnostic and prognostic tools. Furthermore, humanization of the cis p-tau antibody could ultimately be developed as a new treatment for AD, TBI and CTE.     

A stereological study of the effects of mercury inhalation on the cerebellum

Mercury in the environment that arises from organic and inorganic sources can cause irreversible damage to the nervous system. Toxicity may be direct or may arise from interactions with other metals in the environment. We evaluated the possible effects of mercury vapor on rat cerebellum. Twelve adult female rats were divided into control and experimental groups. The rats in the experimental group were exposed to mercury vapor for 9 h/day for 45 days. Cerebellar tissue samples were evaluated using stereology and for histopathology. The total number of Purkinje cells was estimated using a physical disector method. We found that in the experimental group, overall volume decreased and the number of Purkinje cells was reduced. We also found cellular damage including pycnotic nuclei, eosinophilic cytoplasm and vacuolization; these features were absent in the control group. We found that chronic exposure to inorganic mercury vapor is toxic to the cerebellum.     

Cation effects on sol-gel and gel-sol phase transitions of kappa-carrageenan-water system

Sol–gel and gel–sol phase transitions of κ-carrageenan in pure water and in KCl solution were studied using photon transmission technique. Photon transmission intensity, I_tr, was monitored against temperature to determine the sol–gel and gel–sol temperatures (T_sg and T_gs) and activation energies (ΔH_sg and ΔH_gs). It was observed that T_gs was notably higher than T_sg due to the hysteresis on the phase transition loops. T_gs and ΔH_gs values were also higher for gels containing KCl than for those without KCl. The increase in carrageenan content caused an increase in both critical temperatures and activation energies for the gels prepared in pure water and in KCl solution. Increases in the KCl/carrageenan ratio, raised both T_gs and T_sg. Similarly ΔH_sg was elevated by the increase in cation content of the gel. These results were interpreted as the formation of stronger gels in the presence of KCl in water.     

Abnormal Red Cell Structure and Function in Neuroacanthocytosis

BackgroundPanthothenate kinase-associated neurodegeneration (PKAN) belongs to a group of hereditary neurodegenerative disorders known as neuroacanthocytosis (NA). This genetically heterogeneous group of diseases is characterized by degeneration of neurons in the basal ganglia and by the presence of deformed red blood cells with thorny protrusions, acanthocytes, in the circulation.ObjectiveThe goal of our study is to elucidate the molecular mechanisms underlying this aberrant red cell morphology and the corresponding functional consequences. This could shed light on the etiology of the neurodegeneration.MethodsWe performed a qualitative and semi-quantitative morphological, immunofluorescent, biochemical and functional analysis of the red cells of several patients with PKAN and, for the first time, of the red cells of their family members.ResultsWe show that the blood of patients with PKAN contains not only variable numbers of acanthocytes, but also a wide range of other misshapen red cells. Immunofluorescent and immunoblot analyses suggest an altered membrane organization, rather than quantitative changes in protein expression. Strikingly, these changes are not limited to the red blood cells of PKAN patients, but are also present in the red cells of heterozygous carriers without neurological problems. Furthermore, changes are not only present in acanthocytes, but also in other red cells, including discocytes. The patients’ cells, however, are more fragile, as observed in a spleen-mimicking device.ConclusionThese morphological, molecular and functional characteristics of red cells in patients with PKAN and their family members offer new tools for diagnosis and present a window into the pathophysiology of neuroacanthocytosis.