Biomedical subjects
Publications and source records attributed to P Luzi.
A 53-year-old man was diagnosed 8 years earlier with globoid cell leukodystrophy (GLD, Krabbe disease) by his severe deficiency of galactocerebrosidase (GALC) activity. He was found to have eight nucleotide changes on the two copies of his GALC gene, including two in the leader sequence, four considered polymorphisms, and two unique mutations.
Galactocerebrosidase (GALC) is responsible for the lysosomal catabolism of certain galactolipids, including galactosylceramide and psychosine. Patients with GALC deficiency have an autosomal recessive disorder known as globoid cell leukodystrophy (GLD) or Krabbe disease. Storage of undegraded glycolipids results in defective myelin and the characteristic globoid cells observed on pathological examination of the central and peripheral nervous systems. Most patients have the infantile form of GLD, although older individuals are also diagnosed. Recently the human, mouse, and canine GALC genes were cloned, and mutations causing GLD have been identified. We now describe the construction of a vector containing human GALC cDNA (MFG-GALC), and the transduction of cultured skin fibroblasts from molecularly characterized Krabbe disease patients, as well as rat brain astrocytes and human CD34(+) hematopoietic cells, using retrovirus produced by the psi-CRIP amphotropic packaging cell line. The transduced fibroblasts showed extremely high GALC activity (up to 20,000 times pretreatment levels, about 100 times normal). GALC was secreted into the media and was taken up by untransduced fibroblasts from the same or a different patient. Mannose-6-phosphate receptor-mediated uptake was only partially responsible for the efficient transfer of GALC to neighboring cells. Additional studies confirmed the presence of normal GALC cDNA and mRNA in the transduced cells. The GALC produced by the transduced cells and donated to neighboring untransduced cells was localized to lysosomes as demonstrated by the normal metabolism of [14C]stearic acid-labeled galactosylceramide produced from endocytosed [14C]sulfatide.
Infantile Krabbe disease is a severe, fatal autosomal recessive disorder resulting from the deficiency of galactocerebrosidase (GALC) activity. It is relatively common in two separate inbred communities in Israel. In the Druze community in Northern Israel and two Moslem Arab villages located near Jerusalem the incidence of Krabbe disease is about 1 in 100-150 live births. With our cloning of the GALC gene, mutation analysis of these populations was undertaken. The Moslem Arabs were homozygous for two mutations in the GALC gene; a T-to-C transition at CDNA position 1637 (counting from the A of the initiation codon), which is considered a polymorphism and a G-to-A transition at position 1582, which changes the codon for aspartic acid to one for asparagine. The Druze patients are homozygous for a T-to-G transversion at position 1748, which changes the codon for isoleucine to one for serine. Expression studies confirmed the deleterious nature of these mutations. The development of a simple polymerase chain reaction (PCR) amplification and restriction enzyme digestion method to identify these alleles will lead to accurate carrier testing and improved genetic counseling for interested individuals in these communities.
Twenty-one pathologists and technicians participated in a study evaluating the variation present in mitotic counts for prognostication of breast cancer. The participants counted the mitotic figures in 20 breast cancer samples from ten high power fields (mitotic activity index, MAI, giving the results in mitotic figures per 10 fields) and also made a correction for field size and area fraction of the neoplastic epithelium to get the standardized mitotic index (volume fraction corrected mitotic index, or M/VV index, giving the result in mitotic figures per square mm of neoplastic epithelium). The difference in variation between the two methods was not big, but the standardized mitotic index (SMI) showed consistently smaller variation among all participants and different subgroups. Experienced pathologists had the highest variation in mitotic counts, and specially trained technicians, the lowest. The efficiency of the mitotic counts in grading (the grading efficiency) was used to evaluate the mitotic counts. In groups without special training for mitotic counts the mean grading efficiency was lower (experienced and training pathologists both on average had the potential to grade 88% of the cases correctly) than in the group specially trained for the purpose (trained technicians had the potential to grade 95% of the cases correctly). Among the specially trained technicians, the grading efficiency was of the same magnitude as the grading efficiency achieved in determining the S-Phase fraction of cells from paraffin embedded breast cancers by flow cytometry in different laboratories. The results suggest that special training is helpful in making mitotic counts more reproducible, and that in trained hands, the mitotic counts give results comparable to more sophisticated methods of determining proliferative activity in breast cancer.
We identified and cloned the rabbit SP-B gene, encoding the pulmonary surfactant-associated protein, and sequenced its upstream region from -2635 to +428, including a much larger fragment of the upstream region than has previously been reported for an SP-B for any species. Rabbit SP-B showed substantial homology to its human counterpart in the coding and noncoding regions immediately upstream from the TATAA box. Using a luciferase (Luc) reporter gene (luc) construct we measured promoter activity with a 212-bp fragment (SPB212) from nucleotides (nt) -41 to -252, inclusive. SPB212 functioned as an active promoter in this assay. Further, we identified, cloned and sequenced the cDNA encoding a unique DNA-binding protein, N, that bound SPB212 at approx. -195. When the N cDNA was cloned into the expression vector pKC4 and cotransfected with the luc reporter construct, N significantly enhanced Luc production, but only in the presence of dexamethasone. Therefore, we identified and sequenced a functional promoter region upstream from rabbit SP-B, and isolated and characterized a DNA-binding protein that confers enhanced glucocorticoid responsiveness on this promoter.
The deficiency of galactocerebrosidase (GALC; EC 3.2.1.46) is responsible for globoid cell leukodystrophy (GLD, Krabbe disease) in humans and certain animals. This enzyme catalyzes the lysosomal hydrolysis of specific galactolipids including galactosylceramide (galactocerebroside) and galactosylsphingosine (psychosine), among others. Recently we cloned the full-length human GALC cDNA using amino acid sequence information obtained from GALC purified from human urine and brain. In this communication we describe the organization of the human GALC gene. The gene, of nearly 60 kb, consists of 17 exons, which, aside from the first and last, are relatively small, ranging from 39 to 181 nucleotides. The 16 introns range from 247 nucleotides to nearly 12 kb. The 5' untranslated region is GC-rich, containing no perfect CAAT or TATA sequences, similar to genes for other lysosomal proteins. This information will be useful for studies to identify mutations causing low GALC activity in all patients with GLD and to identify the homologous gene in the important animal models.
We identified and characterized two proteins that bind the promoter of surfactant protein B (SP-B) and affect its expression. Proteins A2 and B were identified and their cDNAs cloned and sequenced. Both were novel. They bound a 212-bp functional promoter region at an NF1 site, located between -184 and -198. Effects of these DNAbp on SP-B promoter activity were studied by contransfecting a reporter construct of this 212-bp sequence + luciferase, together with expression constructs for A2 and B into H441 cells. Alone, A2 and B expression elicited modest but statistically significant increases in SP-B promoter activity. When dexamethasone was added, B further increased SP-B promoter activity. For SP-B, basal expression and glucocorticoid responsiveness may involve a number of hitherto unknown gene activators.
Globoid cell leukodystrophy (GLD) of Krabbe disease results from mutations in the galactocerebrosidase (GALC) gene. Previously, we had identified a large deletion in the GALC gene together with a C to T polymorphism at cDNA position 502 in a significant number of cases of infantile Krabbe disease; however, the deletion breakpoint had not been found. In this paper we show that the deletion is approximately 30 kb starting near the middle of the 12 kb intron 10, and includes all of the coding region through exon 17 plus an additional 9 kb. The deletion junction contains a 4 bp direct repeat and is preceded by sequence identified as belonging to the Alu family of interspersed repetitive elements. Using genomic DNA and a PCR-based test to detect normal and deleted sequences at that location, a large number of patients with all clinical types of GLD were analyzed. Of 21 infantile patients found to be heterozygous for the 502T polymorphism reported previously, 15 had the deletion, one could not tested and five, including a Hmong child, did not have the deletion. Sixteen other infantile patients previously tested were found to be either homozygous (10) or heterozygous (6) for the deletion. In addition, five patients with juvenile and adult GLD were found to be heterozygous for the deletion. In every case tested, the deletion was always found on the same allele as the 502T polymorphism. However, other disease-causing mutations have been found on the 502T allele. With careful genotype analysis these families can receive improved genetic information including patient and carrier identification and preimplantation diagnosis.
Galactocerebrosidase (GALC) activity is deficient in all patients with globoid cell leukodystrophy (GLD). While most patients have the severe infantile form of this autosomal recessive disorder (Krabbe disease), patients up to 50 years of age have been diagnosed in this laboratory. With the cloning of the GALC cDNA and availability of information regarding the gene organization, patients can be evaluated for their disease-causing mutations. We now report that a large deletion, together with a polymorphic C to T transition at position 502 of cDNA (counting from the A of the initiation codon), is responsible for a large number of disease-causing alleles in patients with Krabbe disease. Of 48 patients evaluated, 10 were found to be homozygous for the 502/del allele, five patients were heterozygous for this allele, 21 patients were heterozygous for the 502 mutation (presence of the deletion could not be confirmed), and one infantile patient was homozygous for the 502 mutation but at least one allele was not deleted. No patient was found to have the deletion without the 502 polymorphism. The delineation of mutations causing infantile Krabbe disease will provide new information regarding structure-function relationships in this multi-subunit enzyme and will improve the identification of patients and carriers in some families.
Glucocorticoids stimulate surfactant protein-B (SP-B) (expression in type II alveolar cells) by unknown mechanisms. We identified, cloned, and characterized a protein that binds the SP-B promoter. This protein, D, increases the activity of the SP-B promoter in response to glucocorticoid stimulation. Protein D was identified by its ability to bind the SP-B promoter region, which it binds at an NF1 site from -184 to -198 bp. Its binding was abolished by digestion of promoter DNA with BalI, which cuts at -194. Protein D was cloned and sequenced. It is a new DNA binding protein of 33 kDa whose carboxyl end contains a modified basic leucine zipper-like DNA binding motif (bzip). The effects of D on SP-B promoter activity were studied in H441 cells, using a reporter construct containing 212 bp from the SP-B promoter with a luciferase reporter gene (p2121uc), which was cotransfected with a protein D expression construct in which D expression was controlled by the SV40 early promoter. These two plasmids were cotransfected into H441 cells. Without added glucocorticoids, D did not alter SP-B promoter activity. When dexamethasone was added, D strongly enhanced SP-B promoter activity. Identification of this protein suggests that, at least for SP-B, glucocorticoid responsiveness may involve one or more hitherto unknown gene activators.
Both image analysis (IA) and flow cytometry (FCM) may be applied to detect ploidy pattern and cell cycle fractions. However, they have different performance characteristics and may yield different results. The two approaches are applied in this study to 66 breast cancers: IA on imprints and FCM on fresh tissue. The percent coefficient of variation (CV) ranged from 2.0 to 7.0 (mean 5.5; SD 1.1) in IA and from 2.0 to 7.0 (mean 4.4; SD 1.1) in FCM. The values were well correlated. With regard to ploidy pattern, the agreement between the two methods was 92.4%; disagreements were due to four cases being aneuploid by IA but not detected by FCM and one case being aneuploid by IA but tetraploid by FCM. This suggests that IA is capable of detecting aneuploidy with more sensitivity than FCM. In diploid cases, the percent values of cells in G0/G1, S-phase (SPF), and G2M phase were concordant and well correlated. In aneuploid cases, IA was more sensitive than FCM in detecting aneuploid fraction as well as G2M phase, whereas FCM was more sensitive than IA in detecting SPF. A good correlation was found between the DNA indexes (DIs) obtained with the two methods.
Sinonasal non-Hodgkin's lymphomas (SNHLs) of B- or T-cell immunophenotype have been associated with Epstein-Barr virus (EBV) infection of neoplastic lymphoid tissue. Nine SNHLs were investigated using immunohistochemistry, the polymerase chain reaction (PCR) for EBV genome and in situ hybridization (ISH) for EBV encoded RNAs (EBER), immunoglobulin (CI-gHR) and clonal T-cell receptor (CTC beta R) gene rearrangements. Eight cases were diagnosed as peripheral pleomorphic T-cell lymphomas (pPTCL). PCR showed the presence of EBV genome in eight cases; ISH for EBER led to the detection of positive cells in five cases. Late membrane protein (LMP) immunostaining was observed in three cases. No EBV positivity has been detected in control cases. The frequent association with EBV infection in the cases illustrated confirms the previous suggestions that EBV may have a role in the genesis of lymphomas of the sinonasal region.
The aim of this study was to try to place gastric intestinal metaplasia, type III (type III IM) in the stepwise chain of events from atrophic gastritis to cancer. A number of dysplastic, periulcer regenerative, and type III IM lesions were qualitatively diagnosed (and graded) blindly and independently by several pathologists. These lesions were further analysed by means of quantitative parameters, with the aim of differentiating dysplastic from regenerative changes. Inconsistencies between the qualitative and quantitative classification (about 7 per cent of cases) were eliminated and homogeneous groups (low-grade dysplasia, high-grade dysplasia, regenerative changes) were obtained. These cases were taken as the gold standard against which type III IM was compared. The results indicate that the great majority (91.4 per cent) of cases of type III IM fulfil the nuclear and architectural criteria for low-grade dysplasia.
The difficult differential diagnosis between the diffuse variants of cutaneous lymphoid hyperplasia (CLH; synonym; pseudolymphoma) and malignant follicular center cell lymphomas (FCCL) often requires a multidisciplinary approach. Eighteen CLH and 11 FCCL, diagnosed by conventional histology and immunophenotyping and subsequently examined with a polymerase chain reaction to show clonal immunoglobulin heavy-chain gene rearrangements, were subjected to a novel type of automated nuclear image analysis. Of all nuclear parameters tested in azure A-stained semithin sections, the mean nuclear profile area (TN) of lymphoid cells was the best criterion to distinguish between CLH and FCCL (p = 9 x 10(-6)). Additional distinctive features, in the order of decreasing significance, were the SD of TN; all chromatin textural parameters combined; and the light and the dark fractions of the central nuclear profile areas. Parameters related to the chromatin pattern were independent of nuclear profile size in FCCL, but not in CLH. Two lesions registered as CLH displayed the nuclear characteristics favoring this diagnosis, but showed B-cell monoclonality at the DNA level. In conclusion, computerized nuclear image analysis is a helpful additional diagnostic tool in the evaluation of diffuse CLH and cutaneous FCCL.
Diffuse subtypes of cutaneous lymphoid hyperplasia (CLH; n = 18) and primary malignant follicular center cell lymphoma of the skin (FCCL, n = 11) were diagnosed by conventional histology, immunophenotyping on paraffin sections, and gene rearrangement analysis. We then counted on semithin, Azur A-stained sections of resin-re-embedded biopsy specimens the relative numbers of apoptotic bodies among all lymphoid cells (apoptotic index [AI]). The diagnostic value of AI was compared to that of mitotic indices (MI) and percentages of various cell types in the cutaneous infiltrate. Features of cellular infiltrates distinguishing to two groups of lesions, in the order of decreasing significance, were percent large lymphoid cells, percent medium-sized lymphoid cells (both higher in FCCL); percent small lymphoid cells, percent epithelioid/giant cells, and percent histiocytes/macrophages (all three higher in CLH). However, of all parameters tested, AI had the greatest discriminant value (median in FCCL 1.11%, in CLH 0.14%; p = 8 x 10(-6)). Two cases, diagnosed as CLH with all morphologic and immunologic methods used, showed B-cell monoclonality at the DNA level. Linear discriminant analysis determined the following order of distinctive power of variables: 1) AI; 2) MI; 3) percent small lymphoid cells; 4) percent medium-sized lymphoid cells; 5) percent large lymphoid cells; 6) percent epithelioid/giant cells; and 7) percent histiocytes/macrophages. The present study thus establishes AI as an important parameter in the differentiation of diffuse CLH from diffuse cutaneous FCCL.
42 paraffin-embedded squamous cervical carcinomas were screened for the presence of human papilloma virus (HPV; 6b, 11, 16, 18) and for activation of the Ki-ras oncogene family by polymerase chain reaction. In 72% of cases we found one or more HPV types, but no mutations of the Ki-ras gene (codon 12-1 and 61-1, 61-2 and 61-3) were found. We conclude that mutations of the Ki-ras oncogene, at the positions analyzed, are not likely to be involved in the events leading to cervical carcinogenesis.
Abnormal glycosaminoglycan metabolism is involved in the onset of anatomo-functional derangements in diabetic nephropathy, and determines the loss of glomerular basement membrane anionic charges leading to albuminuria. Glycosaminoglycan administration was shown to increase the negative electrical potential of the vessel wall, inhibit mesangial cell proliferation, which is an anatomical hallmark of diabetic nephropathy, and slow down the progression to uremia in subtotally nephrectomized rats, a model that shares some pathogenetic key events with diabetic nephropathy. Based on these considerations, we verified the effect of exogenous glycosaminoglycans on renal involvement in streptozotocin diabetic rats. Long-term administration of two glycosaminoglycans (low-molecular weight heparin and dermatan sulphate) prevented glomerular basement membrane thickening, glomerular anionic charge reduction, as well as the onset of albuminuria without affecting glomerular filtration rate and metabolic control of the disease. Our data demonstrate that the long-term administration of glycosaminoglycans has a favorable effect on morphological and functional renal abnormalities in diabetic rats.
Ontogeny of lung collagen and elastin were studied in fetal rabbit from day 25 to term. Collagen (isolated by hot trichloroacetic acid treatment) and elastin (contained in the residue) were hydrolyzed and the hydroxyproline and desmosine quantitated by hplc. Hydroxyproline slightly increased from day 25 to day 30 (204 to 244 micrograms/100g dry weight). Over the same period desmosine increased from 2.2 to 5.1 micrograms/100 mg dry weight (P < 0.01). The effect of antenatal corticosteroids on the lung of prematurely-delivered fetuses was also evaluated. Betamethasone (B) was given to pregnant does at a dose of 0.2 mg/kg 24 and 48 h before delivery of the fetuses at 26, 27 and 28 days. In treated animals elastin concentration increased significantly by about 22% on day 26 (P = 0.05), by 29% on day (P < 0.02) and by 47% on day 28 (P < 0.02). Hydroxyproline was not affected by steroid treatment at any gestational age. This suggests that steroids affect fetal lung development also via changes in connective tissue.