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Biomedical subjects

P Valentini

Publications and source records attributed to P Valentini.

At least 19 recordsLinked to original sources

Successful treatment with oral valganciclovir in immunocompetent infant with gastrointestinal manifestations of cytomegalovirus infection.

A 3-month-old male infant was admitted to hospital with anemia. Follow-up controls revealed the presence of specific cytomegalovirus (CMV) antibodies. Virus was isolated from urine, blood, and saliva. At 7 months of age, he presented with melena. Polymerase chain reaction (PCR) of biopsy samples from the duodenum was positive for CMV. Anemia resolved after starting antiviral therapy with oral valganciclovir.

Anemia↗

Decreased chemiluminescence in leukocyte adhesion deficiency presenting with recurrent sepsis, amoebiasis and Candida albicans urinary tract infection.

Leukocyte adhesion deficiency (LAD) is a rare disorder of cellular immunity, generally due to various mutations producing reduced or altered expression of membrane integrins. The authors report a case of LAD due to integrins expression imbalance. LAD was suspected after recurrent sepsis, fungal infection and amoebiasis with persistent leukocytosis. Neutrophils were studied with chemiluminescence showing decreased functional activity: up to now, this seems the first chemiluminescence study of neutrophil function and the first report of amoebiasis at the onset in LAD.

Animals↗

Salmonella enterica isolates from faeces of domestic reptiles and a study of their antimicrobial in vitro sensitivity.

From October 2001 to February 2002, the faecal samples of 305 reptiles (165 saurians, 99 ophidians and 41 chelonians) were bacteriologically examined to detect Salmonella enterica. S. enterica was isolated from 73 (23.93%) faecal samples including 44 (60.27%) samples collected from saurians, 15 (20.55%) from chelonians and 14 (19.18%) from ophidians; considering the number of samples taken for each reptile group, S. enterica was isolated from the 36.58% of chelonians, 26.66% of saurians and 14.14% of ophidians. The isolates were distributed among 38 serotypes. Sixty-nine (94.52%) isolates were resistant to erythromycin. About one-third of the isolates was resistant to sulfisoxazole (35.61%), gentamycin (32.88%), amoxycillin (31.51%) and ampicillin (27.40%). All but one of the isolates were sensitive to chloramphenicol. A high percentages of isolates were sensitive to enrofloxacin (84.93%), nitrofurantoin (80.82%), trimethoprim (76.71%) and tetracycline (75.34%).

Animals↗

Measurement device for ankle joint kinematic and dynamic characterisation.

The paper describes a measurement device for obtaining the kinematic characterisation and isometric loading of ankle joints under different working conditions. Non-invasive, in vivo experiments can be conducted with this experimental apparatus, the potential of which could be usefully exploited in basic biomedical research, prosthesis design, clinical applications, sports medicine and rehabilitation. The device determines the 3D movement of the foot with respect to the shank and evaluates the torques and moments around the three articular axes in relation to any desired angular position of the ankle complex. When integrated with superficial electromyographic techniques and electrical stimulation, it allows the assessment of the functionality of the lower leg in both mechanical and myo-electrical terms. The paper reports the main mechanical and electronic features of the device (high linearity; maximum moment ranges +/- 300 Nm for flexion-extension, +/- 35 Nm for both pronation-supination and internal-external rotation; angular ranges: +/- 100 degrees of dorsi-plantar flexion, +/- 50 degrees of internal-external rotation and prono-supination; linear ranges: +/- 25 mm along each axis). Results from a healthy volunteer, under voluntary or stimulated conditions, helped in testing its operatability, reliability, robustness, repeatability and effectiveness. Preliminary simplified protocols have been also applied to 20 healthy volunteers, and the main results were 80.8 +/- 11.9 degrees of internalexternal rotation, 46.2 +/- 9.1 degrees of prono-supination and 74.6 +/- 13.1 degrees of flexion-extension. Torques and moments were normalised with respect to a body mass index of 30. The maximum plantar flexion moment (57.5 + 21.3 Nm) was measured with the foot at 150 of dorsal flexion; the maximum dorsal flexion moment (50.2 + 20.3 Nm) was measured with the foot at 150 of plantar flexion.

Ankle Joint↗

Hepatitis B virus infection in native versus immigrant or adopted children in Italy following the compulsory vaccination.

BACKGROUND: Compulsory vaccination of children against hepatitis B virus (HBV) infection was introduced in Italy in 1991. PATIENTS AND METHODS: To evaluate the current importance of pediatric HBV infection, we studied 359 HBsAg-positive children admitted to 16 centers in Italy from 1991 to 1998. 185 patients were natives of Italy and 174 (39 immigrants and 135 adopted) came from highly endemic countries (eastern Europe: 60.9%, Asia: 16.7%, Africa: 14.9% and Central and South America: 5.7%). RESULTS: Transaminase Levels were moderately altered in both Italian (mean 134 UI/L) and foreign children (mean 168 UI/L). In total, 77% of ItaLian children and 88% of foreign children tested HBeAg positive. High transaminase levels and HBeAg positivity were more frequent in adopted children. Follow-up of 317 patients showed that the incidence of HBeAg/anti-HBe serum conversion was similar in all cohorts, but in adopted children it occurred at an earlier age and was associated with HBsAg clearance in 5%. CONCLUSION: HBV is not frequent in Italian children today, but it is common among children coming from highly endemic areas. The vaccination of nonimmune native populations must be strongly recommended.

Adolescent↗

Seizures in an interferon-treated child.

Interferon-treated patients can present seizures, which in most paediatric cases are related to fever. The case of chronic hepatitis C is described in which Interferon probably disclosed a latent epilepsy. The hypothesis is advanced that seizures can be provoked by Interferon therapy in subjects with a low convulsant threshold and, in those cases in which it cannot be substituted with another drug, antiepileptic therapy should be started after the first episode.

Antiviral Agents↗

T wave alternans detection during exercise stress test and during dobutamine stress. A comparative study in patients with a recent myocardial infarction.

BACKGROUND: Beat to beat electrical alternans of the T wave (TWA) on the electrocardiogram is a risk marker for the occurrence of life-threatening ventricular tachyarrhythmias. Atrial pacing or exercise are commonly used to increase heart rate to the critical level for TWA detection. However, atrial pacing requires invasive procedures while exercise may cause significant noise on the electrocardiographic recording or may be not performed by a number of patients with cardiac diseases. Dobutamine stress testing is routinely used in post-myocardial infarction patients and may represent an alternative means to detect TWA. However, the comparability of data obtained with exercise and dobutamine needs to be proven. METHODS: We measured TWA during exercise and/or dobutamine stress in 42 patients with a recent myocardial infarction. TWA was detected using a commercially available software while the heart rate was increased to the target range of 105-130 b/min. Each patient performed the two tests in random order with an adequate recovery time in between. RESULTS: The mean level of noise during data acquisition for TWA detection was significantly lower during the dobutamine test than during exercise (1.003 +/- 0.67 vs 1.46 +/- 1.20 microV, p < 0.01). With exercise, 32 (78%) patients had a determinable TWA. Of these, 9 (27%) were TWA positive and 23 TWA negative. In the other patients noise (n = 8) or exercise-induced arrhythmias (n = 1) prevented an appropriate TWA determination. One patient could not exercise. With dobutamine stress, 38 (87%) of the 42 patients studied had a determinable TWA. Arrhythmias prevented TWA determination in the remaining 4 patients. Dobutamine and exercise testing provided comparable proportions of TWA determinability. However, by combining exercise and dobutamine testing, a greater (p = 0.0071) proportion of the patients (41/42, 98% vs 32/42, 76%) had a determinable TWA when compared with exercise alone. A comparative TWA study could be performed in 29 patients who completed both the dobutamine and the exercise stress tests. All 22 patients TWA negative at exercise were so at dobutamine testing also. On the other hand, 5 of the 7 patients TWA positive at exercise were so at dobutamine testing also. Overall, 27 (93%) of the 29 patients in whom internal comparison could be performed showed a concordant result. CONCLUSIONS: Dobutamine testing allows TWA detection with results comparable to those obtained at exercise testing. Combining exercise and dobutamine stress allows TWA determination in most of post-myocardial infarction patients. The present study provides the evidence for a safe and effective TWA determination for risk stratification after myocardial infarction.

Adult↗

Gonadotropin-dependent sexual precocity in a boy affected by pseudohypoparathyroidism.

Pseudohypoparathyroidism (PHP) is characterized by hypocalcemia and hyperphosphatemia due to PTH resistance. PHP type Ia is due to diminished G(s)alpha activity in several tissues, causing resistance to hormones whose action is mediated by cAMP. Only two cases of males with PTH type Ia who paradoxically showed sexual precocity have been described in the literature. We describe an 11.5 year-old boy affected by PHP without AHO but with associated true precocious puberty, who came to the I.C.U. for tetanic seizures and drowsiness due to severe hypocalcemia. Hyperphosphatemia, increased PTH levels and normal 25-OH-vitamin D values were present. Skeletal X-ray showed mild osteopenia. Brain MRI revealed symmetric calcifications in basal ganglia and in frontal areas. Thyroid and thyreotropinic function were normal. Testosterone levels were in the adult range, as well as basal and stimulated gonadotropin levels. Tanner stage P4, G4; testicular volume 12-15 mi. Molecular cytogenetics studies are now underway to further elucidate the etiology of this form of PHP.

Bone Diseases, Metabolic↗

Vascular network changes in the retina during ageing in normal subjects: a computerized quantitative analysis.

BACKGROUND: Direct ophthalmoscopic examination of fundus oculi is widely used for the qualitative evaluation of target organ damage in several pathological conditions. At present, there are no reliable techniques available to quantify retinal vascular damage. The aim of this study was to develop a computerized technique for the quantitative analysis of fundus oculi. METHODS: We studied 68 non-smoking, normotensive normal subjects, with a visual acuity > 8/10. From each subject retinal images were taken using a non-mydriatic ophthalmoscope and digitized onto a personal computer. In each image the area of analysis was set to a circular selection, corresponding to 25% of the whole fundus oculi, concentric with the optic disc. From each selection arterial and venous area and mean arteriolar bifurcation angle were obtained. Measurements were taken in a blinded way by two operators and, by the same operator, twice at different times. Parameters were correlated with age and body surface area. RESULTS: Retinal arterial density (arteries 7.44 +/- 1.25%; bifurcation angle 75 +/- 16 degrees) was significantly correlated with age, but not with body surface area. Intra- and interobserver coefficient of variation resulted 2.5 and 3.2%, respectively. CONCLUSIONS: Computerized analysis of the fundus oculi with the evaluation of vascular density indexes represents a simple and reproducible technique that could be useful in identifying changes in retinal vascular network during ageing.

Adolescent↗

Sinus grafting with porous bone mineral (Bio-Oss) for implant placement: a 5-year study on 15 patients.

The efficacy of Bio-Oss as a graft material for sinus floor elevation was studied in 15 patients. A total of 20 sinus augmentation procedures was performed, and 6 months later 57 implants were placed into the augmented sinuses. New bone formation was confirmed in biopsies of 3 patients (new bone: 21.08% +/- 7.25% after 6 mo, 27.55% +/- 4.88% after 12 mo; Bio-Oss: 39.17% +/- 4.36% after 6 mo, 27.01% +/- 11.64% after 12 mo). After a mean loading period of 4.0 +/- 0.5 years (range 3.2 to 4.8 y), 56 implants remained in place. This study confirms Bio-Oss's good osteoconductive properties.

Adult↗

UV- and midwave-sensitive cone-driven retinal responses of the mouse: a possible phenotype for coexpression of cone photopigments.

Molecular biological, histological and flicker electroretinographic results have established that mice have two cone photopigments, one peaking near 350 nm (UV-cone pigment) and a second near 510 nm [midwave (M)-cone pigment]. The goal of this investigation was to measure the action spectra and absolute sensitivities of the UV-cone- and M-cone-driven b-wave responses of C57BL/6 mice. To achieve this goal, we suppressed rod-driven signals with steady or flashed backgrounds and obtained intensity-response relations for cone-driven b-waves elicited by narrowband flashes between 340 and 600 nm. The derived cone action spectra can be described as retinal1 pigments with peaks at 355 and 508 nm. The UV peak had an absolute sensitivity of approximately 8 nV/(photon microm2) at the cornea, approximately fourfold higher than the M peak. In an attempt to isolate UV-cone-driven responses, it was discovered that an orange conditioning flash (lambda > 530 nm) completely suppressed ERG signals driven by both M pigment- and UV pigment-containing cones. Analysis showed that the orange flash could not have produced a detectable response in the UV-cone pathway were their no linkage between M pigment- and UV pigment-generated signals. Because cones containing predominantly the UV and M pigments have been shown to be located largely in separate parts of the mouse retina (), the most probable linkage is coexpression of M pigment in cones primarily expressing UV pigment. New histological evidence supports this interpretation (). Our data are consistent with an upper bound of approximately 3% coexpression of M pigment in the cones that express mostly the UV pigment.

Animals↗

Effects of Laddec on the formation of calcified bone matrix in rat calvariae cells culture.

Osteoblasts from 21 day-old fetal rats calvaria were isolated using a collagenase digestion procedure. Cells were cultured in the presence of Laddec (a highly purified bovine xenograft) and Bio-Oss (natural bone mineral). Optical microscopic observations showed that osteoblasts attached on the plastic culture dishes and formed close contact with biomaterial particles. By day 5, the osteoblasts formed a confluent monolayer. A cytozymatic method showed intense alkaline phosphatase (ALP) staining around and between the substrate granules of the two materials. By day 14, inverted phase microscopic observations showed that osteoblasts formed bone nodules around and between substrate particles. In addition, at this time, the Von Kossa staining was positive. Using a conventional assay, ALP specific activity was higher in the presence of Laddec than in the presence of Bio-Oss. A quantitative morphological method using image analysis showed that the proportion of mineralized bone formed around biomaterial particles in relation to total bone was increased with Laddec (15% more than with Bio-Oss). Ultrastructural observations by TEM showed the presence of an electron dense collagen-free layer at the biomaterial/bone interface and a collagenous matrix deposited at the periphery, indicating the bioactivity of the biomaterials. These results indicated that Laddec increased the expression of ALP in osteoblast cultures and facilitated the formation of multiple cell layers, providing a culture environment suitable for mineralization.

Alkaline Phosphatase↗

Differential activity of glycosaminoglycans on colony-forming cells from cord blood. Preliminary results.

Heparin, heparan sulfate and chondroitin sulfate were evaluated for their possible role on proliferation and differentiation of hematological precursor cells from cord blood. For these purposes, different concentrations of glycosaminoglycans were added to methyl-cellulose in colony assay performed with human cord blood derived cells. A volume of 10 microg/ml heparin induces a significant increase of both granulocyte-monocyte and granulocyte colonies, and a decrease of erythroid-colonies, more evident in the presence of 100 microg/ml. Heparan sulfate-treatment induces a significant increase of all granulocyte-monocyte colonies derived from CFU-granulocyte-monocyte, CFU-granulocyte and CFU-monocyte precursors. A significant decrease of multipotent cells was also observed. On the other hand, chondroitin sulfate induces an increase of granulocyte-colonies and a decrease of erythroid-colonies. Glycosaminoglycans with different structure may be useful to increase the number of specific colonies. The selective and differential binding of glycosaminoglycans with several growth factors and the regulation of their activities is discussed.

Fetal Blood↗

The fundamental and second harmonic of the photopic flicker electroretinogram: temporal frequency-dependent abnormalities in retinitis pigmentosa.

OBJECTIVES: The flicker electroretinogram (FERG) consists mainly of a linear (fundamental, 1F) and a non linear (second harmonic, 2F) component. Previous results indicate that 2F originates more proximally in the retina than 1F, and that retinitis pigmentosa (RP) may affect 2F to a greater extent than 1F. The aim of this study was to evaluate FERG 1F and 2F abnormalities in RP as a function of the stimulus temporal frequency (TF). METHODS: Twelve patients with typical RP and 10 age-matched controls were examined. FERGs were recorded in response to uniform fields (18 degrees) presented in the macula on a light-adapting background. Stimuli were flickered sinusoidally at different, closely spaced TFs between 3.7 and 52 Hz. Amplitudes and phases of the Fourier analysed 1F and 2F components were measured. Components' apparent latencies were estimated from the rate at which phase lagged with TF. RESULTS: When compared to controls, mean 1F amplitudes of patients were reduced at both low (3.7-12.6 Hz) and high (14-52 Hz) TFs, with greatest losses (0.5 log units) around the peaks (3.7 and 41 Hz) of the normal TF function. Mean 2F amplitudes were reduced mainly at low TFs, with greatest losses (0.5 log units) at 5-8 Hz. On average, the shape of the 2F, but not 1F amplitude versus TF function, differed between patients and controls, showing a selective attenuation at low TFs. Mean 1F apparent latencies were delayed at both low and high TFs, with greater delays at low (85 ms) than at high (33 ms) TFs. Mean 2F apparent latencies were delayed only at low TFs (58 ms). CONCLUSIONS: In RP, 1F and 2F phase delays as well as 2F amplitude losses are dependent on TF, suggesting that FERG generators' subpopulations in both distal and proximal retina are differentially affected. Analysis of the FERG TF response is potentially useful to characterize cone system dysfunction in different genetic subtypes of RP.

Adolescent↗