64-slice MDCT arthrography in shoulder instability: our experience

PURPOSE

This study was performed to assess the diagnostic accuracy of air-contrast 64-slice multidetector computed tomography (MDCT) arthrography in the evaluation of glenohumeral joint instability by comparison with conventional arthroscopy.

MATERIALS AND METHODS

Fifty patients with a history of shoulder instability underwent MDCT arthrography with thin collimation scans. The raw data were transferred to a workstation and processed using multiplanar reformation (MPR) and volume rendering (VR) algorithms. All patients subsequently underwent conventional arthroscopy. The results of the two techniques were compared and their sensitivity and specificity calculated.

RESULTS

We diagnosed eight anterosuperior labrum lesions (group 1), 32 anteroinferior labrum lesions (group 2) and two posterior labrum lesions (group 3). Overall sensitivity and specificity (groups 1, 2, 3) were 88% and 100%, respectively. In group 1, sensitivity was only 66% (four false negatives), whereas in groups 2 and 3, it was 94% (two false negatives) and 100%, respectively. The labrum lesions were also found to be associated, with 100% sensitivity and specificity, with 20 lax capsules, 17 Hill-Sachs lesions, five Bankart lesions, two Perthes lesions and three complete rotator-cuff tears.

CONCLUSIONS

Air-contrast MDCT arthrography is fast, reproducible, well tolerated and very accurate in the evaluation of lesions causing shoulder instability.

Interactions of Epstein-Barr virus origins of replication with nuclear matrix in the latent and in the lytic phases of viral infection

Eukaryotic DNA is organized into domains or loops generated by the attachment of chromatin fibers to the nuclear matrix via specific regions called scaffold or matrix attachment regions. The role of these regions in DNA replication is currently under investigation since they have been found in close association with origins of replication. Also, viral DNA sequences, containing the origins of replication, have been found attached to the nuclear matrix. To investigate the functional role of this binding we have studied, in Raji cells, the interaction between Epstein-Barr virus (EBV) origins of replication and the nuclear matrix in relation to the viral cycle of infection. We report here that both the latent (ori P) and the lytic (ori Lyt) EBV origins of replication are attached to the nuclear matrix, the first during the latent cycle of infection and the second after induction of the lytic cycle. These findings suggest that the binding of the origins of replication with the nuclear matrix modulates viral replication and expression in the two different phases of infection.

High glucose modifies heparansulphate synthesis by mouse glomerular epithelial cells

BACKGROUND

Alterations in proteoglycan metabolism are involved in the pathogenesis of diabetic nephropathy. The aim of this study is to evaluate the effects of high glucose on proteoglycan production and to find a reliable in vitro model for the study of diabetic nephropathy.

METHODS

A clone of mouse glomerular epithelial cells was cultured in media containing elevated (30 mmol) and physiological (5 mmol) glucose, or iso-osmolar (30 mmol) mannitol concentrations. We evaluated the synthesis of 35SO4-labeled molecules and the amount of proteoglycans by Sepharose CL6B and DEAE-Sephacel chromatographies.

RESULTS

A clear decrease (56%) in total cell-layer proteoglycan synthesis was induced by 30 mmol glucose, in comparison with normal glucose. A reduction of 25% in medium associated proteoglycan synthesis was observed in high glucose cultured cells. After Sepharose CL6B, in cells cultured in high glucose, cell layer heparansulphate proteoglycan-I (Kav 6B 0. 04) synthesis was reduced by about 81%, heparansulphate proteoglycan-II (Kav 6B 0.21) by about 87% and heparansulphate glycosaminoglycan (Kav 0.4-0.8) by about 91%, respectively. In mannitol-incubated cells the reductions observed were less evident and not significantly different from those in normal glucose.

CONCLUSIONS

These results indicate that (1) glomerular epithelial cells play a central role in proteoglycan synthesis, (2) high glucose modifies the amount and influences the different species production of these macromolecules, while osmotic forces seem to be only partially involved in these effects, and (3) this cellular clone of glomerular epithelial cells can represent a reliable in vitro model for the study of the mechanisms involved in diabetic nephropathy.

[Ozone therapy in lumbar sciatic pain]

INTRODUCTION

Medical ozone is a mixture of oxygen and ozone which can be used for several medical applications. Ozone was first applied clinically to the treatment of lumbar sciatic pain peridurally, while Pietrogrande was the first in Italy to report on its intradiscal administration to treat nucleus polposus herniation. On account of these considerations, we have decided to introduce this method in our Institute (I.C.O.T. Latina) as an alternative to surgery in the treatment of lumbar sciatic pain supported by an intradiscal hernia.

MATERIAL AND METHODS

September, 1995, to April, 1997, we treated more than 1000 patients with intradiscal ozone infiltration. We prospectively analyzed the first 50 patients, with 6 months' follow-up at least; all of them were preliminarily submitted to clinical examination, electromyography, CT and MRI. After local anesthesia, we injected the disk, with 18-20 G needles and under CT or fluoroscopic guidance, with 12 ml of a mixture of oxygen and ozone at a concentration of 20-30 micrograms/ml. The treatment was repeated two or three more times at intervals of 3, 15 or, when necessary, 30 days. After each treatment, CT follow-ups were carried out and the final follow-up was made 3 months later.

RESULTS

We divided our results into clinical and instrumental. As for clinical response, we had 68% positive results (40% excellent, 28% good) and 32% negative results (10% of patients underwent surgery and 22 are under medical and physical treatment). As for CT response, we had 82% positive results (36% excellent, 46% good), while no major changes between pre- and post-treatment CT findings in the remaining 18% of cases.

CONCLUSIONS

Ozone therapy, thanks to its ease of execution and noninvasiveness, permits the successful outpatient treatment of lumbar sciatic pain. Moreover, the lack of major complications and the good results obtained compared to other methods, such as chemonucleolysis, percutaneous automated discectomy, microsurgery and conventional surgery, suggest that ozone therapy can be considered the treatment of choice for lumbar sciatic pain and a valid alternative to surgery in many cases.

Does poly(ADP-ribosyl)ation regulate the DNA methylation pattern?

The existence of a possible correlation between poly(ADP-ribosyl)ation and DNA methylation processes was investigated. In vivo and in vitro experiments were carried out on L929 mouse fibroblasts preincubated for 24 h with or without 3-aminobenzamide, a well-known inhibitor of poly(ADP-ribose) polymerase. Both experimental approaches evidenced a close relationship between these two important nuclear enzymatic mechanisms, suggesting that the poly(ADP-ribosyl)ated isoform of H1 histone and/or long and branched protein-free ADP-ribose polymers could act as protecting agents against full methylation of the CpG dinucleotides in genomic DNA.

H1-H1 cross-linking efficiency depends on genomic DNA methylation

Oligonucleosomal DNA preparations from condensed-inactive chromatin were examined, before and after artificial methylation by bacterial SssI methylase, for their ability to allow cooperative H1-H1 interactions under conditions of different ionic strength. Our results support the conclusion that, within the highly methylated genomic DNA, there are some CpG's whose unmethylated state is critical for chromatin folding. Circular dichroism spectra indicate that artificial overmethylation of native oligonucleosomal DNA reduces its efficiency in inducing an ordered conformation of H1 histone. Temperature melting profiles confirm on the other hand that the native and the artificially overmethylated forms of oligonucleosomal DNA are both able to bind H1 histone.

Autoimmunity to the GM2-1 islet ganglioside before and at the onset of type I diabetes

Recently, the GM2-1 pancreatic islet ganglioside, proposed as a potential autoantigen in type I diabetes autoimmunity, has been biochemically characterized and found to be a novel ganglioside structure. In the present study, we aimed to determine whether an autoimmune response toward this novel islet molecule is 1) present in type I diabetes and is specifically directed against this molecule and not to gangliosides in general and 2) predictive of disease in high-risk subjects. To this end, the following patients have been studied: 1) 24 newly diagnosed type I diabetic subjects, 20 islet cell autoantibody (ICA)-negative first-degree relatives of type I diabetic subjects, and 25 age-matched normal control individuals; and 2) 31 prospectively evaluated ICA+ first-degree relatives of type I diabetic subjects who were followed for up to 10 years, during which 14 of them developed type I diabetes. A direct assay for autoantibodies to GM2-1 and to other pancreatic gangliosides (GM3, GD3, GD1a) was developed using an indirect immunoperoxidase technique performed directly on thin layer chromatography plates. Anti-GM2-1 autoantibodies (all belonging to the IgG class) were expressed in a high percentage of newly diagnosed type I diabetic subjects (71%), while no significant difference was found in the expression of antibodies directed against other pancreatic gangliosides (GM3, GD3, GD1a) among the different groups studied. Anti-GM2-1 autoantibodies were also present in ICA+ relatives (64%) (P < 0.001 vs. control subjects and ICA-relatives): in this group, life table analysis of progression to diabetes showed that anti-GM2-1 autoantibodies were significantly (P < 0.001) associated with disease, occurring in all relatives developing type I diabetes within 5 years and thus identifying a cohort of ICA+ subjects with markedly increased diabetes risk.

[Lesions of the collateral ligaments of the ankle: diagnosis and follow-up with magnetic resonance and ultrasonography]

Acute sprains are one of the most frequent ankle conditions; the lateral collateral ligaments are often involved. Currently, plain radiography and clinical examination are the methods of choice in the management of these injuries. This study was aimed at describing the MR findings of acute ankle sprains, to assess which ligaments are involved, to study the repair process during conservative treatment and, finally, to compare MR and US findings in acute and chronic injuries. We divided our study into a prospective and a retrospective parts. In the prospective study, MRI was performed in 20 consecutive patients with acute ankle sprain diagnosed at the emergency care unit of our institute and treated conservatively with braces. The patients with fractures were excluded. Follow-up was based on a series of MR exams performed every 30 days for 6 months. We diagnosed 18 injuries of the lateral collateral ligaments, 5 of the anterior talofibular ligament (ATFL) (2 partial and 3 complete tears) and 13 of both the ATFL and the calcaneofibular (CFL) (6 partial and 7 complete tears). The follow-up showed complete edema resorption at 30 days in 2 patients with no ligament injuries; the persistence of a medium-large amount of fluid in partial tears at 30 days and its complete resorption at 60 days; and, finally, the persistence of a medium-large amount of fluid at 180 days in 2 complete tears. No scar could be identified in all the patients with ligament injuries. The retrospective study was based on the comparison of MR (gold standard) and US findings in 78 patients with ankle sprain, 28 in the acute and 50 in the chronic phase. In the first group we found 9 ATFL injuries (6 partial and 3 complete tears), 5 ATFL and CFL injuries (3 partial and 2 complete tears), 2 complete tears of lateral collateral ligaments, 3 deltoid ligament (DL) injuries, 2 ATFL and DL injuries and 2 injuries of both lateral and medial collateral ligaments. US was in agreement with MRI in 85% of ATFL, 67% of CFL and 28% of DL injuries; US also yielded 2 false positives in PAA. In the second group of 50 patients, MRI showed 11 ATFL and 8 ATFL and CFL injuries, 3 injuries of lateral collateral ligaments, 6 DL and 8 ATFL, CFL and DL injuries and 5 complete tears of both internal and external collateral ligaments; 10 exams were negative. US had 58% agreement with MRI in ATFL, 46% in CFL and 21% in DL injuries. In this series, US yielded 3 false positives in PAA injuries.

Specific inhibitory effect of H1e histone somatic variant on in vitro DNA-methylation process

H1e and H1c histone variants were purified from mouse L929 fibroblasts using a reverse phase HPLC, and their effect on in vitro DNA methylation was investigated, together with their ability to bind unmethylated or methylated CpG-rich 44bp oligonucleotides. In a "physiological" range of H1:DNA ratios only H1e, at variance from H1c, was found to cause a marked inhibition of in vitro enzymic DNA methylation. It was also shown that both variants have a similar affinity in binding a methylated CpG-rich oligonucleotide, but that the binding to the same oligonucleotide in the unmethylated form occurs preferentially with H1e rather than with H1c. H1e is therefore likely to be directly involved in maintaining CpG-rich sequences in the unmethylated state.

GM2-1 pancreatic islet ganglioside: identification and characterization of a novel islet-specific molecule

Recent studies have indicated that GM2-1, a pancreatic islet monosialo-ganglioside, is an islet-specific component whose expression is metabolically regulable and represents one of the target antigens of cytoplasmic islet cell antibodies. In the present study we aimed to biochemically characterize this molecule using a panel of biochemical techniques including gas chromatography, thin layer chromatography, enzymatic digestion and mass spectrometry. GM2-1 ganglioside was extracted from human pancreas and purified by thin-layer chromatography. Fatty acids in the ceramide (the hydrophobic portion of the molecule), identified by gas chromatography ranged from C16:1 to C24:1. The oligosaccharide chain was enzymatically digested by the sequential application of various exoglycosidases (neuraminidase followed by beta-galactosidase, followed by beta-hexosaminidase) and characterized by gas chromatography identification of the liberated sugars. The following structure was deducted from enzymatic studies and confirmed by mass spectrometry analysis: N-acetyl neuraminic acid-galactose-galactosamine-galactosamine-glucose-ceramide. This is a novel ganglioside structure, not yet described, which shares characteristics with a neuronal glycolipid autoantigen: the LM1 ganglioside. Both GM2-1 and LM1 have a single sialic acid residue in the terminal position, the same migration position on thin layer chromatography and the same number of carbohydrate moieties. In conclusion, we have characterized a novel islet-specific ganglioside molecule with unusual characteristics, such as the terminal sialic acid and the galactosamine residues, which may facilitate both its antigenicity and its involvement in beta-cell autoimmunity.

[CT-guided percutaneous treatment of osteoid osteoma]

CT was used to localize and guide the percutaneous ablation of osteoid osteomas in 11 patients whose age ranged 5 to 63 years. The treatment was performed directly in the CT room ensuring maximum asepsis. General anesthesia was used in children and in vertebral and sacroiliac localizations, while the peripheral block was used in peripheral localizations. In the latter cases, an ischemic band was used to reduce bleeding. A dedicated drill resection system guided by a Kirschner guide wire was used for removal. The treatment was curative in the short period in all the patients, with complete symptom remission. Only one patient required retreatment after 6 months. In our series of patients no major complications, e.g., bleeding or infections, were observed. In 8 cases the resection yielded enough material for histology. To conclude, this technique can be considered a valuable alternative to surgery in the treatment of osteoid osteomas.

Poly(ADP-ribosyl)ation of proteins associated with nuclear matrix in rat testis

We have previously demonstrated that a significant percentage of poly(ADPR) polymerase is present, as a tightly-bound form, at the third level of chromatin organisation defined by chromosomal loops and nuclear matrix. The present work is focused on the study of poly(ADP-ribosyl)ation of proteins present in these nuclear subfractions. It has been shown that, due to the action of poly(ADPR) polymerase, the ADP-ribose moiety of [14C]NAD is transferred to both loosely-bound and tightly-bound chromosomal proteins, which in consequence are modified by chain polymers of ADP-ribose of different lengths. Moreover, histone-like proteins seem to be ADP-ribosylated in chromosomal loops and nuclear matrix associated regions of DNA loops (MARS). A hypothesis can be put forward that the ADP-ribosylation system is functionally related to the nuclear processes, actively coordinated by the nuclear matrix.

Specific variants of H1 histone regulate CpG methylation in eukaryotic DNA

Upon HPLC fractionation of human placenta or calf thymus H1 histone preparations, only some fractions enriched in the H1e-c variants were able to exert a severe inhibition on in vitro enzymatic DNA methylation. These fractions, though similar to the other variants in interacting with genomic DNA, were also the only ones which could bind CpG-rich ds-oligodeoxyribonucleotides (oligos). Both the 6-CpG ds-oligo and the DNA purified from chromatin fractions enriched in 'CpG islands' were good competitors for the binding of H1e-c to the 6meCpG ds-oligo. This ability to bind any DNA sequence and to suppress the enzymatic methylation in any sequence containing CpG dinucleotides suggests, for these particular H1 variants, a possible role in maintaining CpG island DNA and linker DNA at low methylation levels.

Does hypomethylation of linker DNA play a role in chromatin condensation

The inhibitory effect that H1 histone exerts on the in vitro DNA methylation process, catalysed by mammalian DNA methyltransferase, together with the relative hypomethylation of linker DNA in eukaryotic cells chromatin, suggest that this hypomethylated state of linker DNA can be of importance in allowing or regulating H1-dependent chromatin condensation. In native oligonucleosomes (olnu), i.e., in chromatin fragments consisting of 5-20 nucleosomes each, there was a correlation between the effects of H1 on the DNA ellipticity at 280 nm and the in vitro assayed methyl-accepting ability. The same was true in H1-depleted or in H1-reconstituted preparations. Artificial methylation caused olnu DNA to lose its ability to allow cooperative H1-H1 interactions under ionic strength conditions similar to those known to affect the transition of the 10-nm filament to the 30-nm chromatin fiber. These results suggest that hypomethylation of linker DNA plays a role in the H1-H1 interactions that are needed for solenoid condensation.

Binding of histone H1e-c variants to CpG-rich DNA correlates with the inhibitory effect on enzymic DNA methylation

Within the H1 histone family, only some fractions enriched in the H1e-c variants are effective in causing a marked inhibition, in vitro, of enzymic DNA methylation and, in gel retardation and Southwestern blot experiments, in binding double-stranded (ds) CpG-rich oligonucleotides. Both the 6-CpG ds-oligonucleotide and the DNA purified from chromatin fractions enriched in 'CpG islands' are good competitors for the binding of H1e-c to 6-meCpG ds-oligonucleotide. Because of their ability to bind any DNA sequence and to suppress the enzymic methylation in any sequence containing CpG dinucleotides, these particular H1 variants could play some role in maintaining linker DNA at low methylation levels and even in preserving the unmethylated state of the CpG-rich islands which characterize the promoter regions of housekeeping genes.

[Ultra-low field magnetic resonance in the diagnosis of ovarian lesions]

To investigate the diagnostic capabilities of ultra low field MRI in the characterization of adnexal conditions, 46 women (aged 17 to 83 years) with US diagnosis of tubo-ovarian diseases were examined with MRI. An 0.064 T permanent magnet was used (toshiba Access), with T1- and T2-weighted spin-echo (SE) sequences, 3D T1-weighted gradient-echo (GE) sequences and, in 5 patients, a STIR sequence. Compared with surgical (37 patients), needle biopsy (3 patients) and clinical follow-up (6 patients) findings, MR diagnostic accuracy was 86.9%, which is comparable with literature data at higher field strength. The most common diagnostic error in our series was in the differential diagnosis between dermoid cyst and endometriosis which exhibited similar MR patterns. This limitation seems to be overcome by using STIR sequences with 60 ms T1 which, at this field strength, can suppress fat signal completely, whereas blood signal intensity remains high. The MR signal patterns of each group of conditions are also reported: in some cases, such patterns differ from those reported at higher field strength due to different T1 and T2 tissue relaxation times.

Characteristics of proteinuria in experimental diabetes mellitus

An impairment of protein charge selectivity has been invoked to explain the initial anionic proteinuria in diabetic nephropathy. The aims of this work were to investigate charge and size protein perm-selectivity abnormalities in experimental diabetes and to monitor these changes over time after diabetes induction. Diabetes was induced in 56 Sprague-Dawley male rats by streptozotocin; the control group was represented by 38 normal rats. Blood glucose, body weight, urine volumes, and proteinuria in 24-h urine collections were evaluated at 3, 6, 9, and 12 months of diabetes. The Bradford method and mono- and bidimensional gel electrophoresis were used to determine and characterize proteinuria. Body weight increase was lower (P < 0.05, P < 0.0001, P < 0.05 at 3, 6, and 12 months, respectively), urine volumes were greater (P < 0.001, P < 0.005, P < 0.05 at 6, 9, and 12 months, respectively) and the proteinuria was significantly increased (P < 0.05 at 3 months, P < 0.001 at 6 months, P < 0.01 at 9 months, and P < 0.05 at 12 months) in diabetic rats compared with the control group. When the charge and the size of urine proteins were considered, small (30 kDa) and anionic proteins were found to be mainly excreted in diabetic rats, at 3 months of the disease; at 6 months, higher amounts of albumin and cationic proteins with higher molecular weight (50 kDa) were also found in the urine; at 9 and 12 months the changes previously described were associated with an excretion of proteins weighing about 75 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)

Histone-induced condensation of rat testis chromatin: testis-specific H1t versus somatic H1 variants

Due the likely role of H1 histone variants in inducing the formation of folded DNA filaments with different stabilities, the condensing capacity of the testis-specific H1t versus the somatic variants was tested. Circular dichroism analyses of rat testis H1-depleted oligonucleosomes (5-2kbp) revealed that H1t, which appears in germ cells during the meiotic prophase of mammalian spermatogenesis, exerts the lowest condensing effect as compared to the other variants. The distribution of H1 subtypes among different chromatin fractions was also investigated and gave evidence that H1t is more abundant in chromatin regions which are more sensitive to DNAase I digestion.

[Echography, magnetic resonance and double-contrast arthrography of the rotator cuff. A prospective study in 30 patients]

Shoulder pain is a common clinical problem with different etiologies. Without a specific diagnosis, treatment could be ineffective, causing functional limitation, chronic pain and atrophy. US and MRI allow in many cases to correctly define the different etiologies causing shoulder pain, often due to rotator cuff conditions. From June to September 1992, thirty patients with clinically suspected acute or chronic rotator cuff lesion were studied with US, MRI and double contrast arthrography. US and MRI findings were evaluated and compared using arthrography and surgery as the gold standard. The overall accuracy of MRI was 93%: the method yielded accurate information about size and number of rotator cuff tears, and about bursal, bone and muscle involvement. US accuracy was 83% in the diagnosis of large tears, 63% in the diagnosis of small and partial tears and only 11% in the diagnosis of tendinitis. Both MRI and arthrography exhibited high accuracy (respectively 91 and 100%) in the detection of rotator cuff tears when their results were compared with surgical findings. A flow chart to be used in the patients with acute or chronic shoulder pain was drawn from the critical analysis of the above results.

Inhibition of CpG methylation in linker DNA by H1 histone

H1 exerts a specific in vitro inhibitory effect on enzymic DNA methylation. The experiments reported in this paper were undertaken in order to assess whether the lower methylation level found in internucleosomal DNA compared to core DNA is the in vivo consequence of the well-known localization of this histone in the linker region, as opposed to a possible deficiency of CpG dinucleotides in linker DNA. The methyl-accepting ability of H1-depleted oligonucleosomes from human placenta and of the corresponding core particles were assayed by addition of purified DNA methyltransferase, using S-adenosylmethionine as the methyl group donor. We have found that approx. 80% of newly-incorporated methyl groups are localized in linker DNA, which is indeed a good potential substrate for enzymic DNA methylation. Addition of quasi-physiological amounts of H1 to H1-depleted oligonucleosomes markedly reduced their methyl-accepting ability, while exerting a re-condensing effect on these particles, as revealed by the distortions of their circular dichroism spectra.

Effect of H1 histone isoforms on the methylation of single- or double-stranded DNA

The loosely and tightly bound H1 histone isoforms were shown to exert, on the in vitro methylation of linker DNA in H1-depleted oligonucleosomes, inhibitory or activating effects respectively similar to those previously shown in the methylation of Micrococcus luteus dsDNA. When assayed on the enzymic methylation of Micrococcus luteus ssDNA, addition of the tightly bound one resulted in a stimulation similar to that exerted on double-stranded bacterial DNA or on linker DNA from mammalian chromatin, while the loosely bound isoform had no effect whatsoever. The transformation of the "typical" loosely bound H1 isoform into its tightly bound counterpart can be visualized as being an essential event in the modulation of DNA methylation process in eukaryotic chromatin.

[Magnetic resonance and arthroscopy of the knee. A double-blind study in 40 patients]

To evaluate the capabilities of ultra-low-field MR for the high-resolution imaging of the knee with a short acquisition time, a prospective double-blind study was carried out on 40 consecutive patients with acute or chronic articular conditions who were examined with both MR imaging and arthroscopy. Three-dimensional gradient-echo MR sequences were employed which allow many thin high-resolution slices to be obtained in a relatively short time. To evaluate the results arthroscopy, performed the day after MR imaging, was considered the gold standard. MR imaging and arthroscopy were in agreement in 84.6% of meniscal tears with 91.6% sensitivity and 80% specificity, in 82% of anterior cruciate ligament lesions with 100% sensitivity and 80% specificity and in 81% of cartilage lesions with 100% sensitivity and 61% specificity. On the whole, MR imaging and arthroscopy were in agreement in 82.5% of cases with 97.2% sensitivity and 75.3% specificity. MR imaging gave more information about collateral ligament, muscle and bone involvement. These results confirm the capabilities of ultra-low-field MR imaging in the study of the knee: the technique allows diagnostic studies to be performed in a short time, at a low cost, and with similar results to those obtained with higher field strengths.

[Normal anatomy and findings in traumatic pathology of the popliteal system. A MR study]

To date, the lesions of the popliteal system, which are responsible for the so-called postero-lateral knee instability, are still an imperfectly known chapter of knee conditions. We retrospectively analyzed 215 consecutive MR examinations performed May-August 1991 to evaluate MR capabilities in correctly depicting both the normal anatomy and the pathologic conditions of the popliteal system. Using our standard protocols for knee study and two different magnets (0.064 and 0.5 T), we identified 23 lesions of the popliteus and of its meniscal and peritoneal insertions, and 17 lesions involving also other capsular and ligamentous structures of the knee. Coronal T1-weighted images were the best ones to correctly identify normal knee anatomy, whereas sagittal T2-weighted images were more sensitive in detecting popliteal lesions. Our results had clinical or surgical confirmation in all cases.

Histones and DNA methylation in mammalian chromatin. II. Presence of non-inhibitory tightly-bound histones

After removal, by high-salt extraction, of the loosely-bound components present in human placenta chromatin, tightly-bound cationic proteins could be solubilized, by acid extraction, from the 'stripped' chromatin, as well as from the 'stripped' loops or from the 'digested matrix'. These acid-soluble tightly-bound proteins are, in terms of apparent molecular mass and immunoreactivity, quite similar to the 'typical', loosely-bound histones, and, similarly to their 'loosely-bound' counterparts, they can be subdivided in distinct H1-, H2A-, H2B-, H3- and H4-like components, the 'digested matrix' being however characterized by the absence of tightly-bound H1. These tightly-bound histones, at variance from the 'typical' ones, readily find a right-handed helical conformation upon renaturation by progressive dialyses. The H1 components strongly differ also in their effects on enzymic DNA methylation: while 'typical' H1 has a strong inhibitory effect, its tightly-bound counterpart exerts a slight but definite stimulation.

Histones and DNA methylation in mammalian chromatin. Differential inhibition by histone H1

Histones (from calf thymus or from human placenta), if renatured in the presence of EDTA, caused a severe inhibition of in vitro methylation of double-stranded DNA (from Micrococcus luteus) by human placenta DNA methyltransferase. The absence of EDTA during the histone renaturation procedure abolished--at least in the 'physiological' range of the histones/DNA ratio--the inhibition. The H1 component was responsible for this inhibition, no effect being exerted by the other histones. H1 preparations were more effective if renatured in the presence of EDTA--90% inhibition being reached at a 0.3:1 (w/w) H1/DNA ratio. It seems likely that the requirement for the presence of EDTA during the renaturation process is correlated to its ability to induce a fairly stable ordered conformation of the histones, although this effect could also be shown with the 'inactive' H2a, H2b and H3 components, and was instead less evident with histone H1. The restriction to histone H1 of the ability to inhibit enzymic DNA methylation may account for the lower methylation levels present in the internucleosomal DNA of mammalian chromatin.

Persistence of azacytidine-induced SCEs and genomic methylation in CHO cells in vitro

Many carcinogenic agents are able to affect the methylation level in mammalian cells cultivated in vitro. The capacity of azacytidine (AZA) to demethylate DNA can be used to examine the relationship between the genomic methylation level and cytogenetic end-points. Here we compared the sister-chromatid exchange (SCE) level with the genomic % methylcytosine in a Chinese hamster ovary cell line in vitro after giving a single 10-microM pulse of AZA. Both parameters were followed up to 16 cell cycles after the agent was removed. While the SCE level increased starting 2 cycles from the treatment and persisted for the entire 16 cycles, the methylcytosine level, after an initial 50% decrease, approached the control value, completely returning to it after 10 cell cycles. The possibility that the persistence in the SCE increase is an inherited phenomenon is discussed.

[Therapy of hepatic carcinoma by the intra-arterial injection of lipiodol, antineoplastic agents and gelfoam]

Chemoembolization by selective intra-arterial injection of lipiodol--chemotherapeutic agents (mitomycin and/or adriamycin)--followed by terminal embolization with gelfoam was performed on 20 inoperable patients with hepatic tumors: 13 hepatocellular carcinomas (HCC), 6 metastases from colorectal cancer, and one adenoma. A total of 29 embolizations were performed, 17 of them followed by gelfoam embolization. Significant decrease in tumor size or no tumor increase was shown in 8 patients--6 capsulated and well-limited HCC's, and 2 multinodular HCC's. Apart from occasional episodes of post-embolization syndrome (fever, vomit, abdominal pain), no significant complications were observed. Nine patients died at intervals ranging from 2 weeks to 37 months after the first embolization; in 6 patients the cause of death was not related to the advancing of the cancer, but to the complications of the underlying cirrhosis. In cirrhotic patients, damage to the rest of liver parenchyma can be limited by using superselective catheterization. Of the 6 patients with greater than 12 months follow-up, 4 are alive and 2 have died; 2 more patients are still alive 18 months after the first embolization. Finally, lipiodol was useful as radiopaque marker to detect lesion changes during the follow-up.

Glycoprotein distribution in non-histone chromatin proteins from pig liver

Carbohydrate content of non-histone proteins from pig liver chromatin has been measured in different groups of chromatin fractions and does not seem to be related to the affinity of the proteins for DNA. Glycoproteins are preferentially located in the nuclease-sensitive fractions of chromatin. A 59,000 dalton glycoprotein has been identified as a characteristic components of a chromatin fraction solubilized by DNAase II.

Some immunochemical properties of pig kidney DOPA decarboxylase

Antibodies raised in rabbits against pig kidney DOPA decarboxylase show immunological cross-reactivity towards extracts from monkey, beef, rat and rabbit kidney. The influence of the immuno-reaction on the enzymatic activity has been investigated.

Inhibitors binding to L-aromatic amino acid decarboxylase

The effect of a number of inhibitors of L-aromatic amino acid decarboxylase activity on the absorption spectrum of the enzyme-bound coenzyme has been studied. It has been observed that the compounds tested, even if devoid of the amino function and therefore unable to form the Schiff base with the coenzyme, modify significantly the enzyme spectrum, indicating their binding to the coenzyme active site. Spectral modifications suggest that at least two kinds of binding of inhibitors to L-aromatic amino acid decarboxylase may occur, depending on their structural features. Moreover, from the spectra obtained at different concentrations of the inhibitors their affinity constants have been determined: data indicate that the cathecol ring gives the largest contribution to the binding, while the presence of the carboxyl group, the aminic group and the aliphatic chain are responsible for a decrease in the binding, which could be relevant for the efficiency of the catalysis.