Alzheimer disease and cognitive impairment associated with diabetes mellitus type 2: associations and a hypothesis.

INTRODUCTION: Epidemiological studies have demonstrated that patients with diabetes mellitus have an increased risk of developing Alzheimer disease, but the relationship between the 2 entities is not clear. DEVELOPMENT: Both diseases exhibit similar metabolic abnormalities: disordered glucose metabolism, abnormal insulin receptor signalling and insulin resistance, oxidative stress, and structural abnormalities in proteins and ß-amyloid deposits. Different hypotheses have emerged from experimental work in the last two decades. One of the most comprehensive relates the microvascular damage in diabetic polyneuritis with the central nervous system changes occurring in Alzheimer disease. Another hypothesis considers that cognitive impairment in both diabetes and Alzheimer disease is linked to a state of systemic oxidative stress. Recently, attenuation of cognitive impairment and normalisation of values in biochemical markers for oxidative stress were found in patients with Alzheimer disease and concomitant diabetes. Antidiabetic drugs may have a beneficial effect on glycolysis and its end products, and on other metabolic alterations. CONCLUSIONS: Diabetic patients are at increased risk for developing Alzheimer disease, but paradoxically, their biochemical alterations and cognitive impairment are less pronounced than in groups of dementia patients without diabetes. A deeper understanding of interactions between the pathogenic processes of both entities may lead to new therapeutic strategies that would slow or halt the progression of impairment.

MBNL142 and MBNL143 gene isoforms, overexpressed in DM1-patient muscle, encode for nuclear proteins interacting with Src family kinases.

Myotonic dystrophy type-1 (DM1) is the most prevalent form of muscular dystrophy in adults. This disorder is an RNA-dominant disease, caused by expansion of a CTG repeat in the DMPK gene that leads to a misregulation in the alternative splicing of pre-mRNAs. The longer muscleblind-like-1 (MBNL1) transcripts containing exon 5 and the respective protein isoforms (MBNL142-43) were found to be overexpressed in DM1 muscle and localized exclusively in the nuclei. In vitro assays showed that MBNL142-43 bind the Src-homology 3 domain of Src family kinases (SFKs) via their proline-rich motifs, enhancing the SFK activity. Notably, this association was also confirmed in DM1 muscle and myotubes. The recovery, mediated by an siRNA target to Ex5-MBNL142-43, succeeded in reducing the nuclear localization of both Lyn and MBNL142-43 proteins and in decreasing the level of tyrosine phosphorylated proteins. Our results suggest an additional molecular mechanism in the DM1 pathogenesis, based on an altered phosphotyrosine signalling pathway.

Lyn-mediated SHP-1 recruitment to CD5 contributes to resistance to apoptosis of B-cell chronic lymphocytic leukemia cells.

In B-cell chronic lymphocytic leukemia (B-CLL) cells, Lyn, a tyrosine kinase belonging to the Src family, is overexpressed and atypically localized in an aberrant cytosolic complex in an active conformation, contributing to the unbalance between cell survival and pro-apoptotic signals. In this study, we demonstrate that Lyn constitutively phosphorylates the immunoreceptor tyrosine inhibitory motifs of the inhibitory cell surface co-receptor CD5, a marker of B-CLL. As a result, CD5 provides an anchoring site to Src homology 2 domain-containing phosphatase 1 (SHP-1), a known negative regulator of hematopoietic cell function, thereby triggering the negative B-cell receptor (BCR) signaling. The subsequent segregation of SHP-1 into two pools, one bound to the inhibitory co-receptor CD5 in an active form, the other in the cytosol in an inhibited conformation, proves crucial for withstanding apoptosis, as shown by the use of phosphotyrosine phosphatase-I-I, a direct inhibitor of SHP-1, or SHP-1 knockdown. These results confirm that Lyn exhibits the unique ability to negatively regulate BCR signaling, in addition to positively regulating effectors downstream of the BCR, and identify SHP-1 as a novel player in the deranged signaling network and as a potential attractive target for new therapeutic strategies in B-CLL.

Insulin, glucose and glycated hemoglobin in Alzheimer's and vascular dementia with and without superimposed Type II diabetes mellitus condition.

Increased concentrations of insulin, glucose and glycohemoglobin are associated with Type II diabetes mellitus (DM) and recognized as characteristic markers of the disease; in Alzheimer's (AD), Vascular dementia (VaD), and both dementia's with superimposed diabetes (AD + DM, VaD + DM) the knowledge is scarce. The sample (n = 122; males = 60; mean age = 73 +/- 7) comprised DM, AD, VaD, AD + DM, and VaD + DM patients, and healthy controls (C). The ANOVA's yielded significant differences between groups: Insulin p = 3.7 x 10(-3); Glucose p < 10(-12); Glycohemoglobin p = 9.2x10(-4). Comparisons between groups (DM vs. C, AD + DM vs. AD, VaD + DM vs. VaD, and demented DM vs. non-demented DM) resulted significant for all variables (Bonferroni's statistic, alpha = 0.05). Diabetic and diabetic demented patients presented significant increases largely different from controls (0.01 < p < 0.001), unlike the non-significant changes in their non-diabetic counterparts; linear relationships were found across all groups. The correlation's insulin/glucose and insulin/glycohemoglobin change to positive within demented groups, indicating a different performance of insulin in demented and non-demented subjects.

Protein kinase CK2: a newcomer in the 'druggable kinome'.

The acronym CK2 (derived from the misnomer 'casein kinase' 2) denotes one of the most pleiotropic members of the eukaryotic protein kinase superfamily, characterized by an acidic consensus sequence in which a carboxylic acid (or pre-phosphorylated) side chain at position n+3 relative to the target serine/threonine residue plays a crucial role. The latest repertoire of CK2 substrates includes approx. 300 proteins, but the analysis of available phosphopeptide databases from different sources suggests that CK2 alone may be responsible for the generation of a much larger proportion (10-20%) of the eukaryotic phosphoproteome. Although for the time being CK2 is not included among protein kinases whose inhibitors are in clinical practice or in advanced clinical trials, evidence is accumulating that elevated CK2 constitutive activity co-operates to induce a number of pathological conditions, including cancer, infectious diseases, neurodegeneration and cardiovascular pathologies. The development and usage of cell-permeant, selective inhibitors discloses a scenario whereby CK2 plays a global anti-apoptotic role, which under special circumstances may lead to untimely and pathogenic cell survival.

[Peripheral neuropathy in Anderson-Fabry disease: its physiology, evaluation and treatment]. / Neuropatía periférica en la enfermedad de Anderson-Fabry: fisiopatología, evaluación y tratamiento.

AIMS: The purpose of this study was to review the peripheral neurological aspects of Anderson-Fabry disease (AFD). DEVELOPMENT: AFD is a disease caused by lysosomal deposits that was first reported in 1898. This entity has begun to attract renewed interest in recent years because of the progress made in diagnostic techniques and the appearance of enzyme replacement therapy. This pathological condition is transmitted by recessive inheritance linked to the X chromosome and results from a deficiency of the enzyme alpha-galactosidase A, which leads to the accumulation of glycosphingolipids in endothelial and perithelial cells, as well as those of the smooth muscles in blood vessels, the dorsal root ganglia and other structures in the central and peripheral nervous systems. Symptoms during childhood include: neuropathic pain that is predominantly distal in the four limbs (and expresses itself as severe attacks that are often linked to changes in temperature and exercise that interfere with daily activities), hypohidrosis and angiokeratomas. The most serious complications appear during adulthood and include: kidney failure, heart failure and strokes. CONCLUSION: The arrival of enzyme replacement therapy is the first part of a chain in the treatment of AFD, where gene therapy and substrate inhibition therapy are beginning to emerge as real therapeutic alternatives. In spite of all this, at present, the management of painful symptoms is not at all satisfactory for patients and therefore further study and a deeper understanding of the mechanisms involved will allow more specific and effective therapeutic measures to be developed with which to provide patients with greater relief.

[Posterior reversible encephalopathy syndrome: some case reports]. / Sindrome de encefalopatía posterior reversible: presentación de casos clínicos.

INTRODUCTION: In 1996, Hinchey et al described a clinico-radiological picture they called posterior reversible leukoencephalopathy syndrome (PRLS), which is characterized by visual disorders, seizures, altered mental states and changes in the subcortical white matter of the temporoparietooccipital lobes that are shown up in the neuroimages. These clinical manifestations are associated with arterial hypertension. Later, other triggering elements, such as cytostatic drugs, were described without being linked to hypertension. Other authors have suggested the name of posterior reversible encephalopathy, since magnetic resonance imaging (MRI) reveals a high percentage of cortical compromise. CASE REPORTS: We present three cases of posterior reversible encephalopathy with different origins. Two of the cases involved females, one of whom was a 19-year-old hypertensive with lupus nephropathy and the other was a 33-year-old with eclampsia. The third case was an 11-year-old male child with post streptococcal glomerulonephritis and hypertension. The most relevant signs and symptoms included seizures, visual disorders, arterial hypertension and sensory deterioration. MR played a decisive role in diagnosis and it revealed an alteration of the signal in the supra and infratentorial white matter of the cortex and the subcortex, which was predominant in the posterior areas of the encephalon. The three cases presented a significant radiological and clinical improvement in a short time. CONCLUSION: Failure of the self regulation of cerebral vascular circulation, with development of oedema, is the most widely accepted hypothesis to explain the pathophysiological mechanism at work in this entity.

[Electrophysiological evaluation of a case of sensory-motor multifocal acquired demyelinating neuropathy. The effects of immunoglobulin therapy]. / Evaluación electrofisiológica en un caso de neuropatía desmielinizante adquirida multifocal sensitivomotora. Efectos del tratamiento con inmunoglobulina.

INTRODUCTION: Sensory motor multifocal acquired demyelinating neuropathy (SMMADN) is a variant of the chronic multifocal neuropathies. Several reports have been published about the clinical and electrophysiological progression in motor multifocal neuropathy (MMN) prior to and following immunoglobulin (Ig) therapy, but we have found no reports that deal with SMMADN. AIMS: We describe a case of SMMADN in which we conducted a clinical and electrophysiological evaluation before and after therapy with Ig UNC Hemoderivados. CASE REPORT: Female, 40 years of age, who presented asymmetrical weakness in all four limbs which she had been suffering for 12 years. We observed distal muscular atrophies, notable weakness and paresthesias in the four limbs. Electrophysiological studies revealed demyelinating neuropathy with secondary axonal involvement. Intravenous Ig was indicated. We observed a clear improvement in muscular strength, and changes in motor and sensory conduction speeds, but not in the amplitudes of the respective potentials. CONCLUSION: SMMADN is a chronic sensory motor multiple mononeuropathy that begins in the upper limbs and progresses asymmetrically down towards the lower members. The most usual sensory disorders are distal paresthesias. Electrophysiology presents conduction blockages, temporal dispersion, prolongation of the distal latencies, diminished conduction speeds, absence or prolongation of the F wave in one or more motor nerves, and abnormal sensory conduction speed. Accepted treatment is with Ig and, in some cases, with corticoids. In our case, the variations that were obtained could be explained by myelin reconstitution following the immunomodulatory effect of Ig and the axonal involvement that existed due to the secondary sequelae of the inflammatory process.

[Cerebral haematoma in the course of herpes simplex encephalitis]. / Hematoma cerebral en el curso de una encefalitis herpética.

INTRODUCTION: Herpes simplex encephalitis (HSE) is the most common cause of infectious encephalitis at all ages. The usual presentation includes a high temperature, headache and confusion associated with convulsions and signs of a focal neurological deficiency. The typical findings shown by magnetic resonance imaging (MRI) consist of hyperintense lesions, in T2 and FLAIR sequences, especially in the medial and inferior temporal lobe. AIMS. The aim of this paper is to report a case of HSE that associated a cerebral haematoma (CH) in its clinical course. CASE REPORT: A 69 year old female patient who was admitted to hospital because of a syndrome of high temperature, confusion and urinary infection. Studies of the cerebrospinal fluid showed only a slight pleocytosis, and a polymerase chain reaction (PCR) for the herpes simplex virus (HSV) was required. Initial MRI scanning showed an image that was compatible with cerebritis in the left parieto occipital lobe. A later RMI scan revealed a cerebral haematoma in the left parieto occipital lobe, together with new haemorrhagic foci in the bifrontal and in the right temporal lobes. The haematoma was drained surgically and empirical therapy was begun with acyclovir, and later a positive HSV PCR was received. The patient responded favourably to the therapy and was discharged from hospital. DISCUSSION: A variety of atypical presentations in HSE have been reported. Our case presented scant pleocytosis, infrequent lesion topography and coursed with CH. Only a few cases of this last occurrence have been reported in the literature. CONCLUSION: The presence of infrequent features, such as CH, within the framework of the clinical features of encephalopathy cannot exclude the possible existence of HSE.

Cooperative modulation of protein kinase CK2 by separate domains of its regulatory beta-subunit.

Protein kinase CK2 ("casein kinase 2") holoenzyme is composed of two catalytic (alpha and/or alpha') and two regulatory beta-subunits. A truncated form of the beta-subunit lacking its C-terminal region (betaDelta171-215) has lost the ability to stably associate with the catalytic subunits and to display a number of properties which are mediated by structural elements still present in its sequence, notably down-regulation of catalytic activity, autophosphorylation, and responsiveness to polycationic effectors. All these functions are restored by simultaneous addition of a synthetic peptide reproducing the deleted fragment, beta170-215, which is able to associate with the catalytic subunits and to stimulate catalytic activity. This peptide includes a segment displaying significant sequence similarity with a region of cyclin A which interacts with the PSTAIRE motif of CDK2 eliciting its catalytic activity. A peptide reproducing this sequence (beta181-203), but not its derivative in which three nonpolar side chains have been replaced by polar ones, interacts with the alpha-subunit and stimulates its catalytic activity; it also partially restores the ability of truncated betaDelta171-215 to autophosphorylate. These data disclose the essential role of a structural module located between residues 181 and 203 in conferring regulatory properties to the beta-subunit of CK2.

Unique features of HIV-1 Rev protein phosphorylation by protein kinase CK2 ('casein kinase-2').

The HIV-1 Rev transactivator is phosphorylated in vitro by protein kinase CK2 at two residues, Ser-5 and Ser-8; these sites are also phosphorylated in vivo. Here we show that the mechanism by which CK2 phosphorylates Rev is unique in several respects, notably: (i) it is fully dependent on the regulatory, beta-subunit of CK2; (ii) it relies on the integrity of an acidic stretch of CK2 beta which down-regulates the phosphorylation of other substrates; (iii) it is inhibited in a dose-dependent manner by polyamines and other polycationic effectors that normally stimulate CK2 activity. In contrast, a peptide corresponding to the amino-terminal 26 amino acids of Rev, including the phosphoacceptor site, is readily phosphorylated by the catalytic subunit of CK2 even in the absence of the beta-subunit. These data, in conjunction with the observation that two functionally inactive derivatives of Rev with mutations in its helix-loop-helix motif are refractory to phosphorylation, indicate the phosphorylation of Rev by CK2 relies on conformational features of distinct regions that are also required for the transactivator's biological activity.

pCMB treatment reveals the essential role of cysteinyl residues in conferring functional competence to the regulatory subunit of protein kinase CK2.

To assess the functional role of the four conserved cysteinyl residues in the regulatory beta-subunit of protein kinase CK2, the effect of pCMB and other reagents of sulfhydryl groups has been investigated. The pCMB-treated beta-subunit has lost its ability to form either homodimers or regular alpha(2)beta(2) heterotetramers with the catalytic subunit. It also fails to increase catalytic activity toward peptide substrates and to mediate the stimulatory effect of polylysine. The pCMB-treated beta-subunit, however, is still able to prevent calmodulin phosphorylation and to physically interact with the alpha-subunit to form inactive complexes whose sedimentation coefficient is lower than that of CK2 holoenzyme. These inactive complexes upon treatment with reducing agents like DTT are converted into a fully active heterotetrameric holoenzyme.

Tyrosine versus serine/threonine phosphorylation by protein kinase casein kinase-2. A study with peptide substrates derived from immunophilin Fpr3.

Protein kinase casein kinase-2 (CK2) is a spontaneously active, ubiquitous, and pleiotropic enzyme that phosphorylates seryl/threonyl residues specified by multiple negatively charged side chains, the one at position n + 3 being of crucial importance (minimum consensus S/T-x-x-E/D/S(P)/T(P). Recently CK2 has been reported to catalyze phosphorylation of the yeast nucleolar immunophilin Fpr3 at a tyrosyl residue (Tyr(184)) fulfilling the consensus sequence of Ser/Thr substrates (Wilson, L.K., Dhillon, N., Thorner, J., and Martin, G.S. (1997) J. Biol. Chem. 272, 12961-12967). Here we show that, by contrast to other tyrosyl peptides fulfilling the consensus sequence for CK2, a peptide reproducing the sequence around Fpr3 Tyr(184) (DEDADIY(184)DEEDYDL) is phosphorylated by CK2, albeit with much higher K(m) (384 versus 4. 3 microM) and lower V(max) (8.4 versus 1,132 nmol.min(-1).mg(-1)) than its derivative with Tyr(184) replaced by serine. The replacement of Asp at position n + 1 with alanine and, to a lesser extent, of Ile at n - 1 with Asp are especially detrimental to tyrosine phosphorylation as compared with serine phosphorylation, which is actually stimulated by the Ile to Asp modification. In contrast the replacement of Glu at n + 3 with alanine almost suppresses serine phosphorylation but not tyrosine phosphorylation. It can be concluded that CK2 is capable to phosphorylate, under special circumstances, tyrosyl residues, which are specified by structural features partially different from those that optimize Ser/Thr phosphorylation.

Cerebral tumor-like American trypanosomiasis in acquired immunodeficiency syndrome.

Cerebral tumor-like American trypanosomiasis (CTLAT) is an uncommon complication of Chagas' disease, observed only in immunosuppressed patients. We assessed 10 human immunodeficiency virus-positive patients with Chagas' disease who presented with CTLAT. All patients had neurological involvement and 6 developed intracranial hypertension. Neuroimaging studies showed supratentorial lesions in 9 patients, being single in 8. One case had infratentorial and supratentorial lesions. Low CD4+ cell counts were observed in all the cases and in 6 of them CTLAT was the first manifestation of acquired immunodeficiency syndrome. Serological tests for Chagas' disease were positive in 6 of 8 patients. Trypanosoma cruzi was identified in all brain specimens and in three cerebrospinal fluid samples. CTLAT should be considered in the differential diagnosis of intracranial mass lesions in human immunodeficiency virus-positive patients and should be added to the list of acquired immunodeficiency syndrome-defining illnesses.

[Focal dystonia and tremor secondary to brain stem tuberculoma]. / Distonía focal y temblor secundarios a tuberculoma del tronco encefálico.

Brainstem tuberculoma is exceptionally observed. We report a 44 year-old immunocompetent man with proven diagnosis of miliary tuberculosis (TBC) who developed a complex neurological syndrome characterized by right ophtalmoplegia, left-sided hemiparesis and hemihypoesthesia and a gross ipsilateral postural and action tremor with hand dystonia. A ponto-mesencephalic mass was detected by CT and MRI studies of the brain. Clinical, bacteriological and neuroimaging studies allowed to suspect a ponto-mesencephalic tuberculoma. Long-term therapy with anti-TBC drugs and steroids was started, achieving clinical and imaging improvement which retrospectively confirmed the diagnosis. Although with less amplitude, tremor persisted but a complete disappearance of focal dystonia was observed. The pathogenesis of both abnormal movements is particularly discussed since hand dystonia has never been mentioned in the literature as a consequence of brainstem damage.

Chagasic granulomatous encephalitis in immunosuppressed patients. Computed tomography and magnetic resonance imaging findings.

American trypanosomiasis (Chagas' disease), a zoonosis caused by Trypanosoma cruzi with a high incidence in Latin America, may induce an uncommon form of localized encephalitis termed "chagoma", found in few immunocompromised patients. The computed tomography (CT) and magnetic resonance imaging (MRI) findings of brain chagoma are reported for 3 males (ages 32, 32 and 9 yr), the first 2 infected with human immunodeficiency virus (HIV) and the third with acute lymphoblastic leukemia. Diagnosis was confirmed by biopsy. CT disclosed a single, supratentorial, nodular-shaped lesion that substantially enhanced with contrast material, localized in parietal or frontal lobes. T1-weighted MRI showed hypointense lesions that enhanced with gadolinium-diethylenetriaminepentaacetic acid, corresponding to extensive hyperintense areas on T2-weighted images, producing mass effect. The imaging pattern of brain chagoma presented here is similar to that of cerebral toxoplasmosis and should be considered in the differential diagnosis of an intracerebral mass lesion in immunocompromised patients.

HIV-encephalopathy: should we await a catastrophe before screening?

Human Immunodeficiency Virus (HIV)-encephalopathy (formerly AIDS Dementia Complex, or ADC) is characterized by global impairment of intellectual and cognitive functions, personality and behavioral disturbances, decreased memory, inability to concentrate, and apathy. Its motor dysfunction is manifested by impaired speech, gait, and coordination, and by psychomotor retardation. Several scientific reports indicate that ADC may be the earliest, and, at times, the only evidence of human immunodeficiency virus infection, and may present a diagnostic challenge, particularly in the aviation context. Several aviation medicine specialists have pointed out the safety questions raised by this condition when it presents in otherwise asymptomatic individuals. Since October 1985, U.S. military pilots have been tested for the presence of HIV antibody and grounded if found positive. In May 1991, the Executive Council of the Aerospace Medical Association approved a position statement that supports testing of pilots for infection by HIV, and maintains that "individuals confirmed to be infected should be found medically disqualified for flying duties." While bureaucrats delay in resolving HIV mandatory screening, HIV-encephalopathy may be precipitously brought to light, with symptoms involving ocular motor disorders such as dissociated nystagmus, gaze-evoked nystagmus, and impaired saccadic function and smooth pursuit, frequent signs of HIV cerebellar and pontomesencephalic dysfunction.

Complicaciones neurológicas del síndrome de inmunodeficiencia adquirida / Neurological complications of AIDS

El compromiso del sistema nervioso en el SIDA puede producirse por dos mecanismos: a)como consecuencia de la inmunodepresión, por la que se genera la invasión de gérmenes oportunistas o neoplasias y b)por acción viral directa sobre las estructuras neurales. La acción viral directa sería el factor causal de la meningitis aséptica (observada durante el período de seroconversión) y de los trastornos cognitivos, motores y conductales (complejo SIDA-demencia) y la mielopatía observadas en el estadio lV del CDC. La agresión sobre la mielina de estructura subcorticales, tronco cerebral, cerebelo y médula constituirían el substrato anatomopatológico de estas manifestaciones tardías. Los cuadros más comunes vinculados a oportunistas son las encefalitis a citomegalovirus y herpéticas, la leucoencefalopatía multifocal progresiva, los cuadros focales secundarios o toxoplasmosis o tuberculomas y la meningitis criptocóccica. El tumor más común es el linfoma primario de cerebro, observándose con menos frecuencia la invasión por linfoma no Hodgkin o por el sarcoma de Kaposi. Las complicaciones neuromusculares son relativamente frecuentes tanto en el estadio asintomático como en el SIDA. El síndrome de Guillan Barré, observado especialmente durante la seroconversión, así como la polineuropatía inflamatoria desmielinizante crónica y la mononeuropatía múltiple observadas en el estadio asintomático son frecuentemente reportadas y no se diferencian esencialmente de cuadros similares en sujetos seronegativos. En el estadio lV del CDC es habitualmente observada la polineuropatía sensitiva distal, a la que puede asignársele valor de mercado evolutivo. La poliomiositis es el síndrome muscular más frecuente, siendo menos documentados la atrofia selectiva de fibras tipo ll y la miopatía nemalínica