Biomedical subjects

M Anastasi

Publications and source records attributed to M Anastasi.

At least 19 recordsLinked to original sources

PubMed2006

Analysis of the human a-wave ERG component.

The a-wave is one of the main issues of research in the field of ocular electrophysiology, since it is strictly connected with early photoreceptoral activities. The present study proposes mathematical methods that analyse this component in human subjects, and supports experimental evidence relating to possible correlations among the responses of photoreceptoral units under a light stimulus. The investigation is organized in two parts: the first part concerns the onset and the initial slope, up to the first minimum (about 10-15 ms), the second part deals with the main portion of the wave, up to about 30 ms. In both cases, the a-waves, recorded at various levels of luminance, have been fitted with a set of appropriate functions representing possible models of physiological behaviour which would take place in the early stages of phototransduction. The statistical nature of the underlying processes is also discussed. The results indicate that correlations occur in the early stages, whereas random processes are set up later.

Algorithms↗

PubMed2005

Congenital insensitivity to pain with Anhidrosis (NTRK1 mutation) and early onset renal disease: clinical report on three sibs with a 25-year follow-up in one of them.

Congenital insensitivity to pain with anhidrosis (CIPA) is an autosomal recessive disorder caused by mutations in the neurotrophic tyrosine receptor kinase 1 (NTRK1) gene which encodes the receptor for nerve growth factor (NGF). We report the clinical course in three sibs with CIPA and proven NTRK1 gene mutations with a follow-up over a 25-year period in one of them. They had the characteristic clinical features of an abnormally high pain threshold, and mental retardation; in addition their clinical course was marked by the occurrence of early onset renal disease with recurrent microhematuria and proteinuria and frequent observations of increased serum creatinine and blood urea levels. Light microscopy study of a renal biopsy performed in one of them at age of 20 months showed focal glomerulosclerosis, interstitial fibrosis and tubular atrophy. This patient and his younger brother died because of renal failure at the age of 25 years and 14 years, respectively. The sister still alive showed renal impairment and deep venous thrombosis associated with lupus anticoagulant activity, decrease of circulating autoreactive CD5 (+) B lymphocytes and increased urinary levels of IgG and kappa and lambda light chains, suggesting a possible defect in regulation of B-lymphocyte function. In the light of the NGF-related molecular defect, the extraneurological tissue involvement in CIPA might in part reflect dysregulation of immune mechanisms which possibly brings about a chronic inflammatory response. This, in turn, could result in renal disease which should be mentioned among the life-threatening complications associated with this disorder.

Adolescent↗

PubMed2005

Molecular genetics of autosomal dominant retinitis pigmentosa (ADRP): a comprehensive study of 43 Italian families.

Retinitis pigmentosa is the most common form of retinal degeneration and is heterogeneous both clinically and genetically. The autosomal dominant forms (ADRP) can be caused by mutations in 12 different genes. This report describes the first simultaneous mutation analysis of all the known ADRP genes in the same population, represented by 43 Italian families. This analysis allowed the identification of causative mutations in 12 of the families (28% of the total). Seven different mutations were identified, two of which are novel (458delC and 6901C-->T (P2301S), in the CRX and PRPF8 genes, respectively). Several novel polymorphisms leading to amino acid changes in the FSCN2, NRL, IMPDH1, and RP1 genes were also identified. Analysis of gene prevalences indicates that the relative involvement of the RHO and the RDS genes in the pathogenesis of ADRP is less in Italy than in US and UK populations. As causative mutations were not found in over 70% of the families analysed, this study suggests the presence of further novel genes or sequence elements involved in the pathogenesis of ADRP.

Adolescent↗

PubMed2000

Mutations in the CNGB3 gene encoding the beta-subunit of the cone photoreceptor cGMP-gated channel are responsible for achromatopsia (ACHM3) linked to chromosome 8q21.

Achromatopsia is an autosomal recessive disorder featuring total colour blindness, photophobia, reduced visual acuity and nystagmus. While mutations in the CNGA3 gene on chromosome 2q11 are responsible for achromatopsia in a subset of patients, previous linkage studies have localized another achromatopsia locus, ACHM3, on chromosome 8q21. Using achromatopsia families in which CNGA3 mutations have been excluded, we refined the ACHM3 locus to a 3.7 cM region enclosed by markers D8S1838 and D8S273. Two yeast artificial chromosome (YAC) contigs covering nearly the entire ACHM3 interval were constructed. Database searches with YAC content sequences identified two overlapping high throughput genomic sequencing phase (HTGS) entries which contained sequences homologous to the murine cng6 gene encoding the putative beta-subunit of the cone photoreceptor cGMP-gated channel. Using RT-PCR and RACE, we identified and cloned the human cDNA homologue, designated CNGB3, which encodes an 809 amino acid polypeptide. Northern blot analysis revealed a major transcript of approximately 4.4 kb specifically expressed in the retina. The human CNGB3 gene consists of 18 exons distributed over approximately 200 kb of genomic sequence. Analysis of the CNGB3 gene in achromats revealed six different mutations including a missense mutation (S435F), two stop codon mutations (R203X and E336X), a 1 bp and an 8 bp deletion (1148delC and 819-826del) and a putative splice site mutation of intron 13. The 1148delC mutation was identified recurrently in several families, and in total was present on 11 of 22 disease chromosomes segregating in our families.

Amino Acid Sequence↗

PubMed1995

Surgical therapy for obesity can induce a vitamin A deficiency syndrome.

New possible causes and unexplored aspects of the electroretinogram were evaluated in a case of vitamin A deficiency secondary to surgical therapy for morbid obesity. The Naka-Rushton equation, applied to the scotopic b-wave, demonstrated the quantal catch reduction caused by the loss of rhodopsin in the outer segment of photoreceptors. Study of the Fourier analysis of the photopic 20-Hz response suggested a primary involvement of the external retinal layers, with an indirect alteration of the inner layer. The electroretinogram oscillatory potentials showed alterations explained by the involvement of their generators related to the primary photoreceptor lesion.

Adaptation, Ocular↗

PubMed1993

Methodological aspects of the application of the Naka-Rushton equation to clinical electroretinogram.

The nonlinear relation between stimulus intensity and response amplitude of the electroretinogram (ERG) scotopic b wave can be described by a curve based on the Naka-Rushton (NR) equation. Up to now, the NR equation has been used to assess the features of the normal and pathological ERG, but the best approach for a correct evaluation of the parameters is still debatable. The parameters are thought to be related to the different conditions of retinal activities. The method is well known in experimental laboratories but is quite unusual at the clinical level. In the present paper the derivative analysis of the NR function is proposed as an easier approach to understand the variations of the NR parameters in selected pathologies.

Adolescent↗

PubMed1992

Two brothers with a variant of hereditary sensory neuropathy.

We report two brothers with the clinical symptoms and neuropathological findings of hereditary sensory and autonomic neuropathy (HSAN) type IV but with normal sweating function and absence of recurrent fever. We propose that our patients may have a lower degree of expression of the genetic defect underlying HSAN type IV or that they represent a separate genetic entity.

Adolescent↗

PubMed1992

Photopic ERG components in retinitis pigmentosa.

The persistence of a residual flicker electroretinogram 20 Hz response in many cases of retinitis pigmentosa, when the Oscillatory Potentials (OPs) were no longer recordable, led the authors to an investigation by Fourier analysis. The study was carried out in 33 patients affected by different hereditary forms of retinitis pigmentosa revealing recordable 20 Hz flash ERG responses. We applied the Fourier analysis to this ERG response and compared the weight percentage of the first two components to the OP added amplitude. The analysis showed that the 20 Hz flash ERG response contains only the first harmonic in patients with no recordable OPs and both harmonics in patients with recordable OPs. This relationship between OPs and 20 Hz second component, that is possibly related to the activity of inner retina as well as the OPs, can demonstrate an alteration of the inner retina which evolves with distinct electrophysiological features from the ERG photoreceptor impairment.

Adolescent↗

PubMed1989

Influence of crystalline lens on VEP latency in elderly patients.

The study was performed to compare visual evoked potentials of old aphakic and pseudophakic patients (61 to 80 years) with age-matched controls. No differences were found between latencies of the two groups. Thus it seems that increased lens density of old subjects does not influence the processing of the visual stimulus.

Aged↗

PubMed1989

Retinitis pigmentosa and inner retina. Functional study by means of oscillatory potentials of the electroretinogram.

The alterations of the inner retina in retinitis pigmentosa have been described in previous papers less often than the external retina alterations, both from the electrophysiological and morphological point of view. The oscillatory potentials (OPs) of the electroretinogram (ERG) are a good tool to investigate the inner part of the retina because of the deep anatomical location of their generators. We studied the photopic OPs in a group of 25 subjects affected with retinitis pigmentosa and compared them with other ERG components to obtain information about the functional damage of the inner retina. The OPs were recordable in 9 patients. No analogies were found with the inheritance modes. No relationship was found between OPs and 20 Hz ERG photopic response which was still present in a consistent number of eyes when OPs were no longer recordable. Such finding can be interpreted as an expression of inner retinal damage paralleling the photoreceptors and retinal pigment epithelium impairment.

Adult↗

PubMed1989

Incomplete Wolfram syndrome: clinical and electrophysiologic study of two familial cases.

Wolfram, or DIDMOAD, syndrome is a genetic disorder characterized by diabetes insipidus, diabetes mellitus, optic atrophy and deafness. We studied a family in which only diabetes mellitus and primary optic atrophy were present in three female siblings. Two of these patients, fraternal twins, were subjected to a complete electrophysiologic examination. The possibility of an incomplete clinical expression of Wolfram syndrome, hypotheses of its genetic transmission, and diagnostic problems are discussed.

Adult↗

PubMed1987

VECPs and optic disc damage in diabetes.

Abnormal VECP latencies can be found in type 1 diabetic patients without retinopathy or neuropathy. The pathogenesis of this finding is still unclear. The authors report the clinical history of a diabetic patient showing normal fundus, normal oscillatory potentials, and pathological VECP latency on first examination. The clinical follow-up of this patient showed rapid evolution toward proliferative retinopathy. This finding is suggestive of a peripheral (optic nerve or retina) origin of the VECP impairment.

Adult↗

PubMed1987

[Peripheral retinal telangiectasis in retinitis pigmentosa].

The association between retinitis pigmentosa and retinal telangiectasis has been rarely reported. The case of a young woman affected with retinitis pigmentosa and telangiectasis involving bilaterally and symmetrically the inferior retinal periphery is described. Moreover, the patient showed a high degree edema of the retina produced by the permeabilization of the retinal capillaries (especially foveal capillaries) and by the passage of fluid from the choroid through the damaged retinal pigment epithelium. The telangiectasis were successfully treated with cryotherapy. The telangiectasis found in patients with retinitis pigmentosa have to be distinguished from other forms of telangiectasis, as those found in young males or those of the temporal retinal periphery of adults, in which respect they have particular characteristics. The cause of the telangiectasis and of the breakdown of the blood-retinal barrier in retinitis pigmentosa is not know. It is probable that they are produced by a toxic or inflammatory action on the vessels mediated by retinal antigens.

Adult↗

PubMed1986

Optic pathway conduction in insulin-dependent diabetics.

Abnormal latency delay of pattern-reversal visual evoked cortical potentials (VECPs) has been demonstrated in insulin-dependent diabetics without retinopathy as a sign of subclinical damage. Pattern-reversal VECPs and onset-offset (on-off) VECPs probably originated at different cortical levels. On-off latencies of a group of 50 insulin-dependent diabetics without retinopathy or neuropathy and with normal oscillatory potentials have been studied in relation to various clinical and metabolic parameters. The results of our study showed that on-off VECPs have in diabetes the same latency alterations as pattern-reversal VECPs, if to a lesser extent. This finding can be a useful index in the evaluation of patients at risk.

Adolescent↗

PubMed1986

Electrofunctional features of the tilted disc syndrome.

The ERG, EOG and VEPs of 15 patients with tilted disc syndrome were studied. The ERG showed abnormal amplitudes in about 1/4 of the eyes and the EOG values were pathological in 3 patients. It is probable that the abnormality of the inferior-nasal portion of the retina and retinal pigment epithelium seen in the tilted disc syndrome causes the changes in the ERG and EOG. Pattern VEPs latency was delayed in most patients. This finding is probably due to the poor focusing of the light in the retina.

Electrooculography↗

PubMed1986

Clinical patterns and electrophysiological findings in retinal pigment epithelium diseases. Does a correlation exist?

At present it is difficult to distinguish those human chorioretinal diseases in which the retinal pigment epithelium (RPE) is the primary site of dysfunction. This difficulty is caused by several factors such as scarcity of biochemical and histological information and a lack of correlation of basic science information available with the clinical body of knowledge. In the present study we examined 134 eyes at early or late stages of hereditary diseases involving the RPE. We tried to distinguish primary RPE involvement by using standard ERG (a- and b-wave) and EOG testing. We conclude that in general primary RPE damage can be better assessed by current electrophysiology in those diseases which seem to remain localized at the RPE level for a long time.

Adolescent↗

PubMed1986

Involvment of the visual evoked potentials in type I insulin-dependent diabetes.

The visual evoked potentials (VEPs) elicited by pattern stimulation were studied in a group of 62 type I insulin-dependent diabetics. The patients did not have retinopathy. An attempt was made to correlate the duration of the diabetes, insulin requirement, blood glucose and glycosylated hemoglobin with the VEPs. Our study showed that the VEPs of the diabetics have frequently delayed latencies. The VEPs elicited by small checks were more often involved. These stimuli excite the smaller nerve fibers and thus it appears that these fibers are the first to be compromised in diabetes. A positive correlation was found between the VEPs latency and the duration of the diabetes. No correlation was found with the other parameters considered.

Adolescent↗

PubMed1979

Psychotherapy in the goldfish bowl: the role of the indigenous therapist.

The therapeutic advantages and liabilities that accrue to the indigenous therapist (be he professional or paraprofessional) because of the indigenous state were explored, utilizing the five-year experience of ten indigenous therapists in Boston's North End. The current and historical proximity of therapists who live in the same neighborhood as their patients do provides both with increased access to, longitudinal knowledge about, and a blurred role concept of the other that may help or hinder the therapeutic process. Similarities in culture and values can foster alliance formation, differentiation of psychopathology, and therapeutic interventions, but also may interfere when therapy abuts culturally shared blind spots. These data are relevant to the private general psychiatrist as an indigenous therapist in non-metropolitan America.

Allied Health Personnel↗