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Biomedical subjects

M Grasso

Publications and source records attributed to M Grasso.

At least 91 records · Page 5Linked to original sources
PubMed1998

Small diameter, actively deflectable, flexible ureteropyeloscopy.

PURPOSE: We studied and developed ureteroscopic technique and instrumentation beyond our initial experience with small diameter, actively deflectable, flexible ureteropyeloscopy. MATERIALS AND METHODS: Flexible ureteropyeloscopy was performed at 2 university centers in 492 consecutive patients. Endoscope designs and development were based on strict specifications, including 8F or less tip diameter, 3.6F or greater working channel, 2-way active tip deflection and secondary deflection for lower pole intrarenal access. Flexible ureteroscopes manufactured by 5 companies were studied through various prototypic steps and surgical technique. Complementary accessories were developed for specific treatments, including endoscopic lithotripsy, management of urothelial lesions, treatment of upper urinary tract obstruction (that is strictures) and percutaneous access with ureteroscopic assistance in select complex cases. RESULTS: A total of 584 procedures were performed with the small diameter, actively deflectable, flexible ureteroscopes. Flexible ureteropyeloscopic access was always preformed over a working guide wire without an operative sheath. In addition, the 10F dual lumen catheter was the primary device used to obtain 2 guide wires (working and safety), and gently and minimally dilate the intramural segment. Larger dilators were required in only 12% of procedures. The entire intrarenal collecting system was accessed in 94% of cases with lower pole access requiring secondary or passive deflection in 60% of procedures. Endoscopic lithotripsy was the most common procedure performed in this series (303, 52%). Small diameter, flexible ureteroscopy and holmium laser lithotripsy were successful in 97% of patients with ureteral and 79% with intrarenal calculi. When a 2-stage ureteropyeloscopy procedure was used for large upper urinary tract calculi, the success rate for intrarenal calculi increased to 91%. Endoscopic biopsy and treatment of upper urinary tract transitional cell carcinoma were performed in 101 procedures (17%), while retrograde ureteroscopic incision for stricture disease was performed in 36 (6%). The overall major complication rate was less than 1% and there were no ureteral perforations, avulsions, sepsis or deaths. These new endoscopes were more fragile than larger predecessors but a maximum of 30 procedures were performed between interval repair. CONCLUSIONS: Small diameter, actively deflectable, flexible ureteropyeloscopy facilitates various minimally invasive endoscopic therapies. Although this class of endoscope has greater fragility, it is easy to use and has broadened the therapeutic range of ureteroscopic treatment to include intrarenal lesions.

Adolescent↗
PubMed1997

Enteroviral RNA and virus-like particles in the skeletal muscle of patients with idiopathic dilated cardiomyopathy.

The role of chronic viral infection in the etiopathogenesis of idiopathic dilated cardiomyopathy (IDC) has generated considerable research. Enteroviruses were the favorite candidates as etiologic agents of IDC. However, enteroviruses were rarely demonstrated in affected hearts. We investigated whether enteroviral infection persists in the heart and in extracardiac sites, particularly in skeletal muscle, in patients with IDC. Blood and myocardial and skeletal muscle samples were collected at cardiac transplantation from 31 IDC patients, 24 non-IDC heart disease patients, and 3 heart donors. Samples underwent ultrastructural studies and ribonucleic acid (RNA) extraction. RNA was reverse-transcribed, and 2 nested fragments (bps 179 and 126) were amplified in the highly conserved 5' noncoding region of enteroviral genomic RNA. Enteroviral RNA was found in the skeletal muscle of 12 cases, whereas only 4 hearts (2 of which with positive skeletal muscle) were positive. Of the 24 controls, 2 were positive (1 muscle and heart, 1 muscle only). Automated sequencing confirmed the enteroviral nature of the amplified products. Ultrastructural study showed enterovirus-like particles in 4 of the enterovirus-positive muscles, and myopathic changes in all enterovirus-positive cases. Skeletal muscle hosts chronic enteroviral infection in more than one third of patients with sporadic IDC. Two hypotheses may explain this link. Myocardial damage may derive directly from recurrent subclinical heart infections caused by enteroviruses harbored in skeletal muscle. Alternatively, enterovirus-related myopathy may trigger an autoimmune response to antigens shared by muscle and myocardium. Further studies are needed to assess the importance of these, non-mutually exclusive mechanisms in IDC pathogenesis.

Adult↗
PubMed1997

Metastatic prostatic adenocarcinoma presenting as a pituitary mass: shrinkage of the lesion and clinical improvement with medical treatment.

BACKGROUND: Metastatic involvement of the pituitary gland is a very unusual presentation of prostatic cancer. We report a favorable response to medical treatment in such a patient. METHODS AND RESULTS: A 77-year-old man presented with blindness, ophthalmoplegia in his left eye, and mild impairment of memory and mental status. Neuroradiological studies showed a huge intra- and suprasellar lesion that destroyed the sellar floor and extended into the sphenoid sinus. Transsphenoidal biopsy of the lesion demonstrated a prostatic adenocarcinoma. Postoperative studies revealed an enlarged prostate gland and multiple lytic bone lesions. The patient was treated with a combination of leuprolide acetate plus flutamide. Four months later, the patient exhibited a marked improvement in his neurologic status and regained vision in the right eye (visual acuity 6/20). Repeat magnetic resonance imaging of the sellar region confirmed a striking shrinkage of the prostatic metastasis. The clinical status remained stable for 22 months, after which time the disease progressed and the patient died 25 months after beginning treatment. CONCLUSIONS: A favorable response to combined androgen blockade suggests that medical therapy should be considered the therapy of first choice when surgical removal of the metastatic lesion in the pituitary is impossible or too risky.

Adenocarcinoma↗
PubMed1997

Hereditary hyperferritinemia-cataract syndrome: relationship between phenotypes and specific mutations in the iron-responsive element of ferritin light-chain mRNA.

Recent reports have described families in whom a combination of elevated serum ferritin not related to iron overload and congenital nuclear cataract is transmitted as an autosomal dominant trait. We have studied the molecular pathogenesis of hyperferritinemia in two families showing different phenotypic expression of this new genetic disorder. Serum ferritin levels ranged from 950 to 1,890 microg/L in affected individuals from family 1, and from 366 to 635 microg/L in those from family 2. Cataract was clinically manifested in family 1 and asymptomatic in family 2. By using monoclonal antibodies specific for the H and L ferritin subunits, serum ferritin was found to be essentially L type in both normal and affected individuals. The latter also showed normal amounts of H-type ferritin in circulating mononuclear cells; on the contrary, L-type ferritin contents were 13 times normal in family 1 and five times normal in family 2 on average. Serum ferritin was glycosylated in both normal and affected individuals. There was a close relationship between mononuclear cell L-type ferritin content and serum ferritin concentration (r = 0.95, P < .00001), suggesting that the excess production of ferritin in cells was directly responsible for the hyperferritinemia. The dysregulated L-subunit synthesis was found to result from different point mutations in a noncoding sequence of genomic L-subunit DNA, which behaves as an mRNA cis-acting element known as iron regulatory element (IRE). Affected individuals from family 1 were heterozygous for a point mutation (a single G to A change) in the highly conserved, three-nucleotide motif forming the IRE bulge. Affected members from family 2 were heterozygous for a double point mutation in the IRE lower stem. Using a gel retardation assay, the observed molecular lesions were shown to variably reduce the IRE affinity for an iron regulatory protein (IRP), which inhibits ferritin mRNA translation. The direct relationship between the degree of hyperferritinemia and severity of cataract suggests that this latter is the consequence of excessive ferritin production within the lens fibers. These findings provide strong evidence that serum ferritin is a byproduct of intracellular ferritin synthesis and that the L-subunit gene on chromosome 19 is the source of glycosylated serum ferritin. From a practical standpoint, this new genetic disorder should be taken into account by clinicians when facing a high serum ferritin in an apparently healthy person.

Adult↗
PubMed1997

Revisiting the prognostic role of gallium scintigraphy in low-grade non-Hodgkin's lymphoma.

The purpose of this study was threefold: to evaluate the role of gallium-67 scintigraphy in the staging of low-grade non-Hodgkin's lymphomas (LGNHL), to assess the relationship between the expression of CD71 on the surface of the neoplastic cells and the 67Ga uptake by the tumour, and to establish the contribution of 67Ga scan in defining the prognosis of LGNHL. Forty-eight patients with untreated LGNHL diagnosed in a single institution over a decade were reviewed. The end point of the study was survival of the patients according to the scintigraphic 67Ga score at diagnosis. In addition to 67Ga scan, other prognostic variables were studied, relating to the neoplastic burden, the biology of the tumour and the host. Univariate and multivariate analyses were used. 67Ga scan identified only 116/286 (41%) nodes involved by lymphoma that were detected by clinical examination or computed tomography scan. A scintigraphic scoring system with an arbitrary cut-off value of 3 (high scan score) was able to predict patients with a dismal prognosis: with a mean follow-up of 47 months (range: 1-146 months) the median survival time was 28 months in patients with a high scan score and 74 months in patients with a low scan score (P=0.002). CD71 values were 27. 4%+/-14.9% (mean +/-SD) in the former and 8.9%+/-7.2% in the latter (P=0.0001). Only performance status and extranodal sites were significant variables for prognosis in multivariate analysis. It is concluded that 67Ga scan is inaccurate in staging but might be very important in defining the prognosis in LGNHL, in association with other prognostic variables.

Antigens, CD↗
PubMed1997

Pathologic features and clinical outcome after anatomic radical prostatectomy by transcoccygeal approach.

OBJECTIVES: A nonrandomized prospective study was conducted aimed at verifying the clinical outcome and pathologic features of a group of patients submitted to transcoccygeal radical prostatectomy. METHODS: Radical transcoccygeal prostatectomy was performed at our institution in 26 patients after laparoscopic (24 cases) or open surgical (2 cases) pelvic lymphadenectomy. Eighteen patients were selected because they were considered to be at risk for nodal metastases on the basis of preoperative staging (prostate-specific antigen level of 20 ng/mL or greater and/or Gleason score greater than 5); the remaining 8 manifested incidental prostate carcinoma. RESULTS: Intraoperative complications included rectal injury in 1 patient (3.8%) and massive blood loss in another. Transitory leakage at the site of the urethrovesical anastomosis and urethrorectal fistula occurred postoperatively in 2 patients. The rate of positive surgical margins was 26.9%. The mean follow-up time is 27 months (range 3 to 39 months). Total urinary continence was obtained in 21 patients (80.8%); 5 patients (19.2%) still require urinary pads. Four patients (15.4%) have experienced tumor recurrence evidenced only by increased serum prostate-specific antigen levels. Local tumor recurrence with positive biopsy of the urethrovesical junction was diagnosed in 3 patients (11.5%), and 1 (3.8%) experienced systemic tumor recurrence. CONCLUSIONS: Radical transcoccygeal prostatectomy is a safe procedure for the surgical treatment of prostate cancer, both from a clinical and a pathologic point of view. Operative complication as well as pathologic features and clinical outcome reported in this series of patients must be related to selection criteria used in most cases. The exact role of radical transcoccygeal prostatectomy in the clinical setting has yet to be defined. According to these preliminary results, radical transcoccygeal prostatectomy should be further investigated in the treatment of incidental carcinoma after transurethral resection of the prostate or suprapubic prostatectomy and could become an elective indication in such cases.

Aged↗
PubMed1997

Initial use of Browne Pneumatic Impactor.

To determine the safety and effectiveness of the Browne Pneumatic Impactor (BPI), a new pneumatic mechanical lithotripter, in fragmenting urinary calculi. Nine patients were treated between November 1995 and March 1996. The calculi were located in the bladder and urethra in one case, the bladder alone in one case, the distal ureter in six cases, and the proximal ureter in one case. The device was used through semirigid and actively deflectable, flexible fiberoptic endoscopes. All patients were treated on an outpatient basis. Fragmentation of the urinary calculi was successful in all patients when the stone could be reached endoscopically. The device worked irrespective of stone size or composition. There were no intraoperative or long-term complications directly related to the use of the device. All treated patients were stone free at 1-month follow-up, with no evidence of ureteral obstruction. The results of our initial study show that the BPI is a simple, safe, and reliable intracorporeal lithotripter, able to fragment the hardest urinary calculi through semirigid and actively deflectable, flexible fiberoptic endoscopes with no complications related to use of the device.

Adult↗
PubMed1997

Ten-year experience with endomyocardial biopsy in myocarditis presenting with congestive heart failure: frequency, pathologic characteristics, treatment and follow-up.

The present study summarizes our ten-year (1985-1995) experience with endomyocardial biopsy (EMB) in patients with idiopathic congestive heart failure (CHF), with specific reference to frequency of myocarditis, treatment policy, relative benefits, and follow-up. Of the 601 patients who constituted our series, 38 were clinically suspected of having myocarditis on the bases of a very recent onset of congestive heart failure and/or of arrhythmias and/or of conduction disturbances, and of a close-to-recent history of flu-like febrile illness. Corresponding EMBs showed myocarditis in 16 of the 38 cases (42.1%). A further 10 EMBs, from patients with a recent onset of congestive heart failure without prior infection episodes, showed myocarditis. Therefore, biopsy-proven myocarditis occurred in 26 of the 601 patients (4.3%). Of the 26 cases, 21 were lymphocytic, 1 was necrotizing granulomatous, 1 was eosinophilic and occurred in a patient who later developed overt zoonosis, 1 had some giant cells within endocardial inflammatory infiltrates, and 2 were borderline forms. In active myocarditis, inflammatory cells mostly constituted of T-lymphocytes (CD45RO+) with sparse macrophages (CD68+) and a few B cells (CD20+). B-lymphocytes and macrophages, along with activated T-lymphocytes, all expressed MHC class II HLA DR molecules, which were also expressed "de novo" by activated endothelial calls of capillaries and of small intramural vessels. HLA DR revealed itself as a very useful marker for the detection of activated inflammatory and endothelial cells. We also noted an increase in the number of perivascular and interstitial mast cells. Ultrastructural study was helpful for the characterization of myocyte damage and of interactions between inflammatory cells and myocytes. In 4 cases (1 of whom was later revealed as HIV positive, and subsequently died of AIDS), we found microreticulotubular structures in endothelial cells of small vessel and capillaries; in 7 cases, there were myocyte changes similar to those described in polymyositis; in 1 case, we observed subplasmalemmal buddings, but no viral particles; in 6 cases, there was extensive myocyte damage with myofibrillar lysis and focal adipous metaplasia; the remaining 6 cases showed myocyte damage of differing extent and severity; in the borderline forms, such damage coexisted with interstitial fibrosis. One of the 21 lymphocytic myocardites was not treated because during hospital screening the patient proved to be HIV positive; of the remaining 20 active myocardites, 11 were treated with a 6-month tapered steroid and azathioprine protocol (one was treated for 24 months), while 9 were not treated. The corresponding follow-up was: 6 deaths (congestive heart failure), 2 cardiac transplants and 3 survivals (1 with pace-maker) in the treated group, and 3 deaths (2 of congestive heart failure and 1 of sudden death), 1 cardiac transplant and 5 survivals (1 on the waiting list for transplantation) in the non-treated group. One of the 2 patients with borderline myocarditis died of congestive heart failure, and 1 is alive. Of the 22 patients with clinical diagnosis of myocarditis and negative biopsy, 7 died of congestive heart failure (2 on the waiting list for transplantation), 4 underwent cardiac transplantation, and 11 are alive (1 is awaiting transplantation). Of the 20 patients currently alive, 1 was originally in NYHA class III, 15 were in class II and 4 were in class I. Of the 20 overall patients who died, 12 were originally in NYHA class IV, 6 in class III, 2 in class II; of the 8 patients who underwent transplantation, 6 were originally in NYHA class IV and 2 in class III. Our overall experience shows that the frequency of myocarditis diagnosed according to Dallas criteria is high in patients with clinical diagnosis of myocarditis, while it is extremely low in dilated cardiomyopathy patients. This finding suggests that, although non-specific, recent onset of symptoms and prior febrile infe

Adolescent↗
PubMed1997

Factors increasing the risk of allograft vascular disease in heart transplant recipients.

Allograft vascular disease is the major cause of late cardiac graft failure. A multifactorial etiopathogenesis is supposed. Our study investigated factors associated with allograft vascular disease occurrence. After stratifying our series on the basis of potential risk factors, we calculated allograft vascular disease incidence rate in 267 grafts from 258 patients who underwent transplant between November 1985 and August 1996. Chi-square test was used for the identification of univariate risk factors to be included in a multivariate model. Multivariate analysis was based on a Poisson model. Seventy of the 267 grafts (26.2%) were diagnosed with allograft vascular disease. Heart disease other than idiopathic dilated cardiomyopathy, donor's age, number of mismatches for HLA-B = 2, presence of systo-diastolic hypertension, number of acute rejection positive endomyocardial biopsies > or = 7 and the association of human Cytomegalovirus and hepatitis C virus infections proved to be univariate risk factors, and were included in the Poisson multivariate model. The association of Cytomegalovirus and hepatitis C infections multiplied allograft vascular disease incidence rate by 3.9, systo-diastolic hypertension by 2.2, occurrence of 2 HLA-B mismatches by 2, a high number (> or = 7) of acute rejection positive-endomyocardial biopsies by 1.8, and heart disease other than idiopathic dilated cardiomyopathy by 1.8. The association of human Cytomegalovirus and hepatitis C virus infections, of HLA-B mismatches, of acute rejection-positive endomyocardial biopsies, as well as post-transplantation hypertension and native heart disease other than idiopathic dilated cardiomyopathy, proved to be positively associated with an increased risk of allograft vascular disease. Given the concordance of our data with those of numerous prior series, we are going to adopt a special surveillance angiographic protocol for patients with these factors.

Adolescent↗
PubMed1996

Regulation of tumor necrosis factor-and Fas-mediated apoptotic cell death by a novel cDNA TR2L.

A novel cDNA, TR2L, isolated from murine NIH 3T3 fibroblasts, was found to modulate tumor necrosis factor (TNF)-mediated apoptosis in murine L929 fibrosarcoma cells. The full-length cDNA (853 bp) encodes a predicted coding region of 56 amino acids (6.3 kD), with 53.6% identity to the C-terminus of rat transcriptional activator FE65. When expressed stably in L929 cells, TR2L protein inhibited TNF cytotoxic response. In contrast, TR2L enhanced anti-Fas antibodies/actinomycin D (ActD)-mediated L929 apoptosis. Alteration of TR2L function occurred by tagging this protein with a 6xHis fragment to the N-terminus (designated 6xH-TR2L). L929 cells which stably expressed 6xH-TR2L acquired a significantly enhanced TNF apoptotic response and increased genomic DNA fragmentation compared to control cells. Enhanced cell death also occurred in these 6xH-TR2L-expressing cells under serum starvation conditions. In contrast, the anti-Fas/ActD-mediated apoptosis was blocked by the 6xH-TR2L protein. Functional role of TR2L protein in regulation of cancer cell susceptibility to TNF-and Fas ligand-mediated apoptosis is suggested.

3T3 Cells↗
PubMed1996

Frequency and characteristics of coronary thrombosis in the epicardial coronary arteries after cardiac transplantation.

We investigated at autopsy or at retransplantation the frequency and characteristics of coronary thrombosis in 76 cardiac allografts: 37 in place for < or = 2 months (early) and 39 in place >2 to 99 months (late). The 76 allografts were inserted in 69 patients: a single 1 in 56 patients and 2 allografts in 13 patients, 7 of whom subsequently died and had an autopsy. An average of 140 sections from 70 5-mm-long segments of 8 epicardial coronary arteries were examined from each of the 76 allografts with both hematoxylin-eosin and Movat pentachrome stains. Thrombus was found in only 1 coronary artery (3%) (the right one) of the 37 early allografts, and in 24 of 39 late allografts (61%). Of the latter 39 grafts, 29 (79%) had allograft vascular disease (AVD) and 24 (83%) of them had coronary thrombosis. Of the 312 epicardial coronary arteries (4 major and 4 minor) examined in the 39 late cases, 66 arteries (21%) contained thrombus. Of the 24 late cases with thrombus in at least 1 artery, thrombus was present in 66 (34%) of the 192 epicardial coronary arteries examined: in 6 of the 8 arteries in 3 patients; in 5 arteries in 2 patients; in 4 arteries in 1 patient; in 3 arteries in 5 patients; in 2 arteries in 6 patients, and in a single artery in 7 patients. In all 66 arteries with thrombus (24 patients) the thrombus was longer than 5 mm. The thrombus in the late cases was entirely nonocclusive (mural) in 51 (77%) of the 66 epicardial coronary arteries containing thrombus and entirely occlusive in 10 arteries (15%). It consisted exclusively of multiluminal channels in 6 arteries (9%) and combinations in 1 artery (2%). Acute myocardial infarcts were present in 3 patients, all of whom had occlusive thrombi. In all 10 arteries with occlusive thrombi, the thrombus was larger than the underlying plaque and no occlusive thrombi were located over ulcerated plaques. These observations demonstrate that thrombus is common in epicardial coronary arteries >2 months after cardiac transplantation.

Adolescent↗
PubMed1996

Premutation for the Martin-Bell syndrome analyzed in a large Sardinian family: III. Molecular analysis with the StB12.3 probe.

This report complements a series of clinical, cytogenetical, and psychological studies previously reported on a large Sardinian pedigree segregating for premutations and full mutations associated with the Martin-Bell syndrome (MBS). Using the StB12.3 probe, we report now the molecular classification of all of the critical members of the pedigree. These molecular findings are evaluated against the variable phenotypic manifestations of the disease in the course of a six-generation segregation of an MBS premutation allegedly present in a common female progenitor of 14 MBS male patients and 9 female MBS heterozygotes seen in the last two generations. The nature and stepwise progression of MBS-premutations toward the fully manifested Martin-Bell syndrome and the possibility of reverse mutational events toward the normal allele are discussed with respect to the application of the presently available diagnostic tools in genetic counselling.

B-Lymphocytes↗
PubMed1996

Molecular and cytogenetic analysis of the fragile X syndrome in a series of 453 mentally retarded subjects: a study of 87 families.

We report on a series of 453 mentally retarded subjects investigated for fragile X syndrome from 1982 to July 1995. The 22% rate of efficiency of FRAX positivity indicated a significant preselection by the clinicians. However, this rate dropped to 11% in the last year. Since 1992, Southern blot analysis was extended to include family members of the 87 positive subjects, for a total of 442 individuals examined with the probe StB12.3. In addition to premutated (118), fully mutated (148), and pre/full mutation mosaic subjects (27), 14 atypical cases were found. Some of these cases are described in more detail. In particular, we report on the hybridization and polymerase chain reaction data of 2 fragile X subjects with full mutation and a 2.8-kb allele and 1 with full mutation and a 2.4-kb allele. An intellectually normal male with 18% of fraXq27.3 and an unmethylated full mutation is also described. Finally, a mentally retarded child with only a lower allele of 2.7 kb is presented.

Chromosome Aberrations↗
PubMed1996

Prenatal diagnosis of 30 fetuses at risk for fragile X syndrome.

The results of 30 prenatal diagnoses for fragile X syndrome are reported. Amniotic fluid cells were examined in 1 case, fetal blood in 4, and chorionic villi samples in the others. Of the 5 fetuses analyzed by cytogenetic methods, 1 had showed 4% of fraXq27.3 expression sites and the pregnancy was terminated. For 1 diagnosis, linkage analysis was used: the female fetus turned out to be normal. In 24 fetuses, the direct analysis of the mutation by StB12.3 probe was performed: 6 female and 3 male fetuses were found to carry a full mutation and 1 female fetus was found to carry a premutation. In 3 cases, the diagnoses were verified on fetal blood samples. Several tissues of 2 aborted male fetuses were analyzed for the fragile X mutation. The results are reported and discussed.

Chorionic Villi Sampling↗
PubMed1996

Fragile X founder chromosomes in Italy: a few initial events and possible explanation for their heterogeneity.

A total of 137 fragile X and 235 control chromosomes from various regions of Italy were haplotyped by analyzing two neighbouring marker microsatellites, FRAXAC1 and DXS548. The number of CGG repeats at the 5' end of the FMR1 gene was also assessed in 141 control chromosomes and correlated with their haplotypes. Significant linkage disequilibrium between some "major" haplotypes and fragile X was observed, while other "minor" haplotypes may have originated by subsequent mutation at the marker microsatellite loci and/or recombination between them. Recent evidence suggests that the initial mechanism leading to CGG instability might consist of rare (10 (-6/-7)) CGG repeat slippage events and/or loss of a stabilizing AGG via A-to-C transversion. Also, the apparently high variety of fragile X chromosomes may be partly due to the relatively high mutation rate (10 (-4/-5)) of the microsatellite markers used in haplotyping. Our fragile X sample also showed a higher than expected heterozygosity when compared to the control sample and we suggest that this might be explained by the chance occurrence of the few founding events on different chromosomes, irrespective of their actual frequency in the population. Alternatively, a local mechanism could enhance the microsatellite mutation rate only on fragile X chromosomes, or fragile X mutations might occur more frequently on certain background haplotypes.

Alleles↗
PubMed1996

Different effect of height on latency of leg and foot short- and medium- latency EMG responses to perturbation of stance in humans.

In standing humans, platform perturbations evoked short- (SLR) and medium-latency responses (MLR) in soleus (Sol), tibialis anterior (TA) and flexor digitorum brevis (FDB) muscles. The latency of all responses significantly increased with subjects' height. The slope of the regression lines for the MLRs versus height was significantly steeper than that for the SLRs. The conduction velocity of the afferent fibres mediating the FDB MLR, calculated on the basis of the regression, was 17.5 m/s. These findings indicate that the MLRs are transmitted through afferent fibres slower than those mediating the SLRs. While the latter fibres are spindle group Ia afferents, the former are suggested to be group II fibres.

Adolescent↗