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Biomedical subjects

G Monga

Publications and source records attributed to G Monga.

At least 19 recordsLinked to original sources
PubMed2000

JC virus in human glial-derived tumors.

To investigate the presence and the role of polyomaviruses JC (JCV), BK (BKV), and the simian polyomavirus (SV40) in human brain tumors, samples from 25 glial-derived tumors (10 astrocytomas, 5 ependymomas, 5 oligodendrogliomas, and 5 glioblastomas) were examined by means of molecular biology and immunohistochemistry. Nested PCR of the large T (LT) region and its sequence analysis showed JCV in 6 cases (4 astrocytomas, 1 oligodendroglioma, and 1 ependymoma), while the transcriptional control region (TCR) was amplified only in 1 astrocytoma, the oligodendroglioma, and the ependymoma, one of which (astrocytoma) also stained positively by immunohistochemistry (JCV LT). TCR sequence analysis of the oligodendroglioma showed a JCV rearranged structure not related to a known viral strain, while the astrocytoma and the ependymoma disclosed a JCV Mad-4 strain that is known to induce brain tumors in animals. We suggest that JCV could have played a role in the pathogenesis of these brain tumors.

Adolescent↗
PubMed1999

BK virus renal infection in a patient with the acquired immunodeficiency syndrome.

BACKGROUND: We describe herein a patient with the acquired immunodeficiency syndrome and renal failure due to biopsy-proven BK virus (BKV) infection. Three months after the diagnosis of the renal viral infection, his condition remained unchanged. Although BKV has previously been shown to be associated with ureteral stenosis and renal damage in renal transplant patients, to our knowledge, the literature contains only 3 cases describing the presence of BKV lesions in the kidneys of immunosuppressed patients who had not undergone transplantation. METHODS: The presence of BKV infection was demonstrated by means of histology, immunohistochemistry with polyclonal anti-SV40 antibody, immunoelectron microscopy, polymerase chain reaction, and enzymatic cleavage with BamHI. RESULTS: Histologic examination revealed interstitial inflammatory infiltrates and tubules with enlarged and eosinophilic nuclei. CONCLUSIONS: The high frequency of latent BKV infection and its reactivation during immunosuppression suggest that the possibility of its involvement in renal damage should be considered in immunocompromised patients.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Demonstration of multiple HPV types in laryngeal premalignant lesions using polymerase chain reaction and immunohistochemistry.

Recent evidence has shown that human papillomavirus (HPV) is involved in both the development of carcinoma and in premalignant mucosal lesions of the oral cavity. This study examined the relationship of HPV infection to some pathological features in precancerous lesions of the larynx, not examined extensively so far. Fifty formalin-fixed paraffin-embedded tissue sections containing human laryngeal precancerous lesions were screened for the presence of HPV infection by polymerase chain reaction, and for capsid protein expression by immunohistochemistry with polyclonal antibody directed against the L1 protein. The presence of HPV DNA was detected in 28 of 50 specimens (56%), including 9/12 cases with mild dysplasia (75%), 3/6 cases with moderate dysplasia (50%), and 7/11 cases with severe dysplasia (64%). Multiple HPV infections, containing two or three types, were detected in 17 of the 28 HPV-positive lesions (60%). Of 21 cases with keratosis and no dysplasia, 11 were positive for HPV DNA (52%) and 4 showed L1 staining (36%). By contrast, L1 positivity was revealed only in two lesions with moderate dysplasia, confirming that fully productive HPV infection is strictly dependent on epithelial differentiation and surface keratinization. The probability that HPV is a cofactor in the malignant progression of these lesions is suggested by the fact that 3/4 patients who developed cancer within 50 months were positive for HPV DNA.

Adult↗
PubMed1998

Renal Encephalitozoon (Septata) intestinalis infection in a patient with AIDS. Post-mortem identification by means of transmission electron microscopy and PCR.

We describe the occurrence of renal Encephalitozoon (Septata) intestinalis infection in a 35-year-old AIDS patient who died with disseminated tuberculosis. The patient did not complain of specific symptoms involving the kidney or lower urinary tract during life, but at autopsy, light microscopic examination of the kidney revealed numerous small round or oval bodies in the tubules and tubular cell cytoplasm that were interpreted as intracellular protozoa. Transmission electron microscopy of tissue retrieved from paraffin-embedded samples identified these organisms as microsporidia belonging to the Encephalitozoonidae family, but did not allow definitive identification of the species of infecting parasite. This was made possible only by means of Southern blot hybridization after the polymerase chain reaction, which recognized the micro-organism as E. intestinalis.

AIDS-Related Opportunistic Infections↗
PubMed1998

Ultrastructural and immunohistochemical findings in Alport's syndrome: a study of 108 patients from 97 Italian families with particular emphasis on COL4A5 gene mutation correlations.

A total of 108 patients affected by Alport's syndrome, taken from 97 families, were enrolled in a genetic and ultrastructural study. Sixty-four families (75 patients) were X-linked, seven autosomal recessive, two autosomal dominant, five uninterpretable, and 19 sporadic. The ultrastructural features were consistent with Alport's syndrome in 66, doubtful in 20, and not significant for Alport's syndrome in 22 patients in the X-linked, sporadic, and genetically uninterpretable groups (without significant differences), as well as in the autosomal group. Mutations of the COL4A5 gene were present in 36 patients in the first three groups, without significant differences. More severe mutations were more frequently present in patients with an ultrastructural pattern consistent with Alport's syndrome. Nevertheless, there seems to be no strict correlation between mutation and ultrastructure, because a major rearrangement was found in a patient with no significant lesions, and different morphologic patterns were detected in patients Belonging to the same family. Immunohistochemical investigation into 24 patients for alpha (IV) chains showed that both alpha 3(IV) and alpha 5(IV) were lacking in the glomerular basement membrane of 13 patients (five with mutations) and were expressed in another six (three with mutations and one in the autosomal group). On the contrary, in this study the retained expression of alpha 3(IV) chain was found, despite the lack of alpha 5(IV) in the glomerular basement membrane of five patients (two with mutation). These different patterns could be related to both the type and severity of the COL4A5 mutations. All of the ultrastructural patterns were identified in all three immunohistochemical groups. Ultrastructural features and alpha 5(IV) chain production, even if an expression of a genetic mutation, do not strictly correlate. The combined use of analysis of collagen expression and electron microscopy made it possible to diagnose Alport's syndrome in 92% of the cohort, and therefore this approach is advisable. A multidisciplinary approach is recommended in the study of Alport's syndrome in an attempt to achieve a better diagnostic definition of and insight into the pathogenetic mechanisms.

Adolescent↗
PubMed1998

PCR detection of JC virus DNA in the brain tissue of a 9-year-old child with pleomorphic xanthoastrocytoma.

Pleomorphic xanthoastrocytoma (PXA) is a rare cerebral tumor of young adults with a slow growth and a good prognosis. Due to its peculiar histopathological findings, the tumor resemble to the lytic phase of progressive multifocal leukoencephalopathy (PML), a JC Virus (JCV) induced disease. For these reasons, the presence of JCV genoma and viral particles were searched for by means of nested polymerase chain reaction (nPCR) and electron microscopy (EM) in a 9-year-old child with PXA. Although EM did not reveal any viral particles, nPCR did reveal genomic sequences of the LT, R, and VP1 regions of JCV. Sequence analysis showed that the R region was mutated with respect to the archetypal form thus yielding the Mad 4 variant of JCV previously reported as being oncogenic in animals. We suggest that JCV may have played a role in the development of this tumor.

Astrocytoma↗
PubMed1998

[Assessment of clinical competence of medical school graduates in Italy with standardized patients. The opinion of the examinees].

An international collaborative project for the evaluation of clinical competence at the end of the Medical School curriculum using the ECFMG-CSA (Educational Commission for Foreign Medical Graduates--Clinical Skills Assessment) prototype was started in Italy in April 1996. Faculty representatives from Italian Medical Schools and experts from the ECFMG in Philadelphia participated in the Project. The CSA consists of integrated clinical encounters with 10 standardized patients during which the examinee is asked to obtain a focused history, perform a relevant physical examination and communicate initial diagnoses and management plan to the Standardized Patient (SP). The SP then completes checklists that are scored by Faculty members. The project was concluded in Spring 1998 and a total of 173 new graduates were examined. The data elaborated by the primary site in Chieti University will be available in the Fall 1998 by the ECFMG in Philadelphia. This preliminary communication reports the opinions of the examinees on the ECFMG-CSA, contained in the questionnaires administered after the test. Most of the examinees considered this new methodology as a valid tool for the assessment of clinical competence, especially history-taking and interpersonal skills and stated that the SP simulations were realistic. The 72% of examinees indicated that the Medical School curriculum does not adequately prepare for the CSA examination. Lastly, 68% was in favour of including the SP in the Medical Licensing Examination.

Clinical Competence↗
PubMed1997

Hepatic histology of patients with HIV infection and chronic hepatitis C treated with interferon.

AIMS: To evaluate the histological changes seen in liver biopsies after interferon (IFN) treatment in patients with chronic hepatitis C and human immunodeficiency virus (HIV) infection. METHODS: Twenty four intravenous drug users with chronic hepatitis C were investigated histologically before beginning a 12 month course of IFN treatment and 18 months later. Twelve were HIV positive, without opportunistic or other viral infections (group A), and 12 were HIV negative (group B). RESULTS: According to alanine amino-transferase concentrations, four sustained responders and eight non-responders were found in group A; six sustained responders, five relapsers, and one non-responder were found in group B. HCV RNA became negative in one sustained responder of group A and in the six sustained responders of group B. When histological findings of biopsies performed before therapy and 18 months later were compared, no significant changes in the mean value of Knodell's index and subindices were found in group A, whereas in group B Knodell's index, piecemeal necrosis, and focal hepatocellular necrosis decreased significantly. CONCLUSIONS: In chronic hepatitis C, coinfection with HIV showed a tendency towards a lower response to IFN, although this did not reach statistical significance; however, none of the HIV positive patients developed cirrhosis during the follow up and this should be considered in clinical management of such patients.

Adult↗
PubMed1997

Renal changes in patients with acquired immunodeficiency syndrome: a post-mortem study on an unselected population in northwestern Italy.

The renal pathologic features of 120 consecutively autopsied patients affected by acquired immunodeficiency syndrome was investigated by light microscopic analysis. Variously associated renal changes were found in 82 patients (68.3%). Glomerular changes were present in 25. The following diagnoses were made: mesangial glomerulonephritis (16 patients), defined by the presence of deposits in the mesangium and/or mesangial cell proliferation; membranous glomerulonephritis (4 patients), cirrhotic glomerulosclerosis (2 patients); and lupuslike glomerulonephritis (3 patients). Glomerular diseases seemed to be significantly associated with chronic hepatitis or liver cirrhosis. Interstitial inflammation was present in 19 cases: chronic pyelonephritis (2 patients), focal nephritis (5 patients), multiple cortical abscesses (7 patients), granulomatous nephritis (5 patients). Cryptococci were found in one and undetermined microorganisms in two cases of multiple cortical abscesses. Atypical mycobacteria were found in two cases of granulomatous nephritis. Mycotic infections were identified in another 6 patients, in whom they did not elicit any inflammatory response. It is worth stressing that, although various generalized infections are common in patients with acquired immunodeficiency syndrome, only cryptococci and atypical mycobacteria also frequently involve the kidney. Focal tubular necrosis was observed in 15 patients. Benign nephrosclerosis was the most common vascular change (27 patients). Changes recalling hemolyticuremic and localized intravascular coagulation were found in three and six patients, respectively. Our data, dealing with a European Caucasian population, considerably differ from those reported in North American literature, in as much as we found no cases of human immunodeficiency virus nephropathy. Conversely, immune-mediated glomerular diseases were frequent, in agreement with recent studies on renal biopsy specimens from AIDS patients with acquired immunodeficiency syndrome. This type of infections, supplies multiple sources of antigens that may stimulate immune complex formation and, therefore, glomerular diseases.

Acquired Immunodeficiency Syndrome↗
PubMed1997

GAS6, the ligand of Axl and Rse receptors, is expressed in hematopoietic tissue but lacks mitogenic activity.

GAS6, a gene previously identified as growth arrest specific, has been demonstrated to be the ligand of Axl, a novel tyrosine kinase receptor widely expressed in both normal and neoplastic hematopoietic tissue. We have observed previously that GAS6 mRNA was present in whole bone marrow. This preliminary finding prompted us to investigate the presence of GAS6 in hematopoietic tissue and the possible role of this molecule in controlling the proliferation of hematopoietic precursors. We report here that the protein GAS6 is diffusely present in hematopoietic tissue, both in stromal and in hematopoietic cells, and that, among these cells, positivity is observed in megakaryocytes and myelomonocytic precursors. Furthermore, our data suggest that GAS6 is not a growth factor for hematopoietic progenitors or stromal fibroblasts. Despite the fact that both the Axl receptor and its ligand, GAS6, are expressed in hematopoietic tissue, the biological role of their interactions remains to be determined.

Biopsy↗
PubMed1996

Apparent preferential loss of heterozygosity at TSC2 over TSC1 chromosomal region in tuberous sclerosis hamartomas.

To investigate the molecular mechanisms of tuberous sclerosis (TSC) histopathologic lesions, we have tested for loss of heterozygosity the two TSC loci (TSC1 and TSC2) and seven tumor suppressor gene-containing regions (TP53, NF1, NF2, BRCA1, APC, VHL, and MLM) in 20 hamartomas from 18 TSC patients. Overall, eight angiomyolipomas, eight giant cell astrocytomas, one cortical tuber, and three rhabdomyomas were analyzed. Loss of heterozygosity at either TSC locus was found in a large fraction of the informative patients, both sporadic (7/14) and familial (1/4). Interestingly, a statistically significant preponderance of loss of heterozygosity at TSC2 was observed in the sporadic group (P < 0.01). Among the possible explanations considered, the bias in the selection for TSC patients with the most severe organ impairment seems particularly appealing. According to this view, a TSC2 defect might confer a greater risk for early kidney failure or, possibly, a more rapid growth of a giant cell astrocytoma. None of the seven antioncogenes tested showed loss of heterozygosity, indicating that the loss of either TSC gene product may be sufficient to promote hamartomatous cell growth. Finally, the observation of loss of heterozygosity at different markers in an astrocytoma and in an angiomyolipoma from the same patient might suggest the multifocal origin of the second-hit mutation.

Chromosome Deletion↗
PubMed1996

Simulation of right atrial cardiac myxoma by silent hepatocellular carcinoma.

A clinically silent hepatocellular carcinoma presenting as a mixoma of the right atrium is described. Intra-atrial growth has been reported in advanced, clinically manifested cases of liver carcinomas in African and Japanese subjects, but very occasionally in Caucasian people. Our case further suggests that this occurrence should also be considered in Western Countries.

Aged↗
PubMed1996

Intracellular protozoan infection in small intestinal biopsies of patients with AIDS. Light and electron microscopic evaluation.

Small intestinal biopsies of 21 patients with acquired immunodeficiency syndrome (AIDS) with light microscopic findings diagnostic or suspicious for parasite infection were investigated by transmission electron microscopy (TEM). TEM allowed us to identify and specify the genus and species of involved parasites in 16 out of the 21 cases: 7 Cryptosporidium parvum, 5 Enterocytozoon bieneusi and 4 Isospora belli. Cryptosporidium was easily identified on light microscopy (LM), and only slightly influenced by parasite burden in all the 7 cases; TEM confirmed LM diagnosis and made it possible to characterize the parasites as C. parvum. The identification of Microsporidium on LM in our cases was related to the burden of parasite; its presence was certainty identified in 2 cases and suspected in 3. TEM allowed to identify these parasites as E. bieneusi. Intracytoplasmic coccidia could be detected with certainly in semithin sections in all 4 cases, but TEM was always needed to specify the infectious agent as I. belli. In 5 cases the suspicious of protozoan infection on LM (3 microsporidia, 1 intracytoplasmic coccidia and 1 Cryptosporidium) was not confirmed by TEM. Our data suggest that TEM is an appropriate diagnostic tool in this field of pathology and necessary in most of the cases.

Acquired Immunodeficiency Syndrome↗