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.

Linkage analysis identifies gene carriers among members of families with hereditary nonpolyposis colorectal cancer

BACKGROUND & AIMS

Uncertainty about genetic risk in hereditary nonpolyposis colorectal cancer (HNPCC) may lead to unnecessary screening. The aims of this study were to show how gene linkage findings can elucidate who is at risk and requires intensive screening and how cancer control can be enhanced by screening high-risk family members. This information can be useful given the public health magnitude of HNPCC.

METHODS

An extended family with HNPCC was studied using formal linkage analysis with DNA extraction from blood samples, followed by genotyping with polymerase chain reaction technique for microsatellite markers. Sixty-one blood relatives of a family with HNPCC, 5 of whom had colorectal cancer, and 12 unrelated family members underwent DNA sampling for genetic analysis.

RESULTS

Linkage analysis showed that all 5 affected individuals had a haplotype with the same alleles 10/7/9, which was also detected in 13 first-degree healthy gene carriers and absent in the remaining 43 non-gene carriers. In the asymptomatic subjects screened, one incidental colorectal cancer and four adenomas were detected in 3 of 6 gene carriers. An adenoma was found in 1 of 17 noncarriers; the remaining 16 noncarriers have undergone 67 unnecessary colonoscopies.

CONCLUSIONS

Linkage analysis can differentiate gene carriers from non carriers. Colorectal cancer screening should be restricted to gene carriers.

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.

[Ambulation after fracture of the femur: recuperation in Parkinsonian and hemiplegic patients]

One hundred and twenty-seven patients with femour fractures were studied with the aim of verifying the possible influence of Parkinson's disease and hemiplegia on ambulation recovery. Participating in this study were 31 patients with Parkinson's disease, 36 patients with hemiplegia and 60 patients without any neurological damage. After rehabilitation, 61.1% of hemiplegic, 40% patients without neurological damage and 29% of parkinson disease patients reached the same ambulation capacity level present before the fracture. Patients suffering from Parkinson disease showed an important loss of ambulation which was statistically significant compared to the control group. The loss of deambulatory capacity was not statistically significant in hemiplegic group. According to the authors' opinion, this result depends on correlated damages or on poor collaboration typically present in patients with Parkinson disease.

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.

p53 oncoprotein overexpression correlates with mutagen-induced chromosome fragility in head and neck cancer patients with multiple malignancies

In this study, we analysed immunocytochemically p53 expression in first primary and second primary cancers from 25 head and neck cancer patients (HNCPs) with multiple malignancies in comparison with oncoprotein expression in tumour tissues from 25 historical HNCP controls with single cancer in a match-paired analysis. Moreover, we investigated bleomycin-induced chromosome fragility in both groups of HNCPs and in 21 additional healthy controls. Thirty-nine out of 75 tumour specimens analysed (52%) showed positive p53 immunostaining. Eleven out of 25 (44%) from single cancer patients and 28 out of 50 (56%) tumours from HNCPs with multiple malignancies were p53 positive. In the group of multiple primary cancers, nine patients (36%) showed positive staining of both first and second primaries, whereas six (24%) had positive labelling of first primary cancer but not of the subsequent second primary, four (16%) patient showed p53 expression only in the second primary cancer and six (24%) patients showed no p53 immunoreactivity in both tumours. Chromosomal analysis demonstrated a higher sensitivity to clastogens of HNCPs with multiple tumours than of HNCPs with a single cancer (P < 0.01), and a significant correlation between chromosome fragility and p53 overexpression (P < 0.01) only in HNCPs with multiple malignancies more than in those with single head and neck cancer (P = 0.11). Moreover, we found that patients with p53-positive staining of both first and second primaries showed a statistically significant higher mutagen sensitivity than those with a single p53 immunoreactive tumour or those in whom both cancers were p53 negative (P < 0.01). Our data suggest that subjects with increased susceptibility to carcingogens after exposure to tobacco or alcohol are at higher risk for multiple cancers in which one of the most common genetic events is aberrant p53 expression.

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.

Immunolocalization of alpha 2, alpha 5, and alpha 6 integrin subunits in salivary tissue and adenomas of the parotid gland

The localization of the integrin subunits alpha 2, alpha 5, alpha 6 was studied immunohistochemically in samples of normal salivary gland and in a series of 8 pleomorphic adenomas, 5 Warthin's tumors, and 2 basal cell adenomas. In normal salivary tissue, acinar and ductal cells expressed alpha 2 and alpha 6 chains at the basal cell pole facing the basement membrane. alpha 2 also localized at sites of cell-cell contact. No staining of the epithelial component was seen with alpha 5. The polarized expression of alpha 2 and alpha 6 subunits was retained in salivary adenomas. These subunits were present at the basal cell pole of solid nests, tubules and ducts of pleomorphic adenomas, as well as of the basal layer of the epithelium of Warthin's tumor, and of the trabecular structures of basal cell adenomas. The alpha 5 subunit was consistently expressed only by cells embedded in the myxoid or chondroid matrix of pleomorphic adenomas. We conclude that the pattern of a integrin subunit expression in salivary adenomas may be related to the "epithelial" or "mesenchymal" phenotype of the neoplastic cells.

Perineal reconstruction with continent colostomy after the Miles operation

Since the beginning of the century, different surgical procedures have been employed to create new anal sphincters for a continent perineal colostomy after abdominal perineal anorectal resection for cancer. After a detailed review of all the currently employed surgical procedures, the authors present their experience with 15 cases treated by transposition of the gracilis muscles to the perineum. More than 50% of the operated patients had good functional results with complete continence for solid stools and sufficient control of the stimulus. Poor results are related to surgical complications or unexpected postsurgical diseases and cancer recurrence or metastases. This surgical procedure seems to be an interesting possibility for selected patients in the case of a permanent abdominal incontinent colostomy after the Miles operation.

[The efficacy of creatine phosphate in the treatment of patients with heart failure. Its echographic evaluation after acute and protracted treatment]

The hemodynamic effects of acute and long-term administration of creatine phosphate were studied in 23 patients with heart failure (NYHA classes II and III) under stabilized treatment. Acute creatine phosphate (5 g i.v.) induced a significant increase of the ejection fraction (FE) and of other parameters of cardiac contractility. Once these improvements of cardiac contractility were obtained by acute treatment, further significant increases in cardiac function were observed if treatment was continued for six days, i.e. telesystolic diameter and volume, as well as parietal stress were significantly reduced, and ejection fraction and shortening fraction were significantly increased. Creatine phosphate treatment has a favourable influence on the hemodynamics of patients with an obvious contractility deficit and chronic ischemia of the myocardium.

Pigmented villonodular synovitis of the temporomandibular joint: report of a case

Pigmented villonodular synovitis is a benign reactive process of the synovial tissue, that usually involves the knee or other major joints. Reports of this entity in the temporomandibular joint are rare. The authors describe a case involving this joint, initially clinically diagnosed as a parotid tumour.

[Predictive value of various echocardiographic parameters of systolic and diastolic function in the development of congestive heart failure after infarction]

To evaluate the predictive value of systolic and diastolic left ventricular (LV) function parameters, in the development of congestive heart failure (CHF) after acute myocardial infarction (AMI), 48 patients (mean age 56.2 +/- 10.4 years) were studied with two-dimensional and Doppler echocardiography (2D echo) in the acute phase (36 +/- 12 hours) and after 6 months of follow-up. The following parameters have been evaluated: LV wall motion score-index; peak velocity of early diastolic filling (E); peak velocity of filling during atrial systole (A); the ratio A/E; percent of LV filling contributed by atrial systole (A%). During follow-up 10 patients (Group B; 21%) developed symptoms and/or signs of CHF, while 38 patients (Group A; 79%) did not. In the patients who developed CHF 2D echo showed a depressed contractile function (mean value of wall motion score-index 3.08 +/- 0.45 versus 3.53 +/- 0.32 of Group A; p < 0.001) and a marked impairment of filling during atrial systole: A/E = 1.89 +/- 0.80 versus 1.07 +/- 0.35 (p < 0.001); A% = 52.2 +/- 9.9 versus 39.1 +/- 8.4 (p < 0.001). The multivariate analysis showed that the ratio A/E, A% and the wall motion score-index are the only variables that may predict the development of CHF. This capacity has been confirmed also considering the cut-point as conditional variables (A/E > 1.4; A% > 45%; score-index < 3.1). Our results demonstrate that a combined evaluation by 2D echo of systolic and diastolic LV function parameters allowed a better stratification of patients at risk of developing CHF after an AMI.

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.

[A comparison between the "bithermal caloric test" and the "hot monothermal with simultaneous cold test"]

Hot (44) and cold (30) caloric test are the most common tool to investigate canal activity. Many authors, otherwise, have pointed out that this method is very long needing about five minutes of interval among the irrigations and that it is often troublesome for the patient that is exposed four times to a vertigo. To investigate vestibular function some of these authors tried to use the hot monothermal test alone but results were poor. The aim of this study was to propose a shorter and a less troublesome method of investigation and to introduce a new diagnostic possibility not pointed out with traditional caloric test. We have tried to determine some new reliable diagnostic criteria modifying confidential value of the hot monothermal test and considering the eventual presence of the nystagmus and its direction during the cold simultaneous test; on the basis of this results we are able to distinguish a normal vestibular function from a labyrinthine preponderance or a directional preponderance or an aspecific disfunction. When the vestibular function is normal or when there is a labyrinthine preponderance our results are in total accord with those achieved with the traditional bithermal test. Therefore we suggest to use always the hot monothermal test associated with the cold simultaneous test, performing the two cold irrigations in additions, only in the case of a directional preponderance or an aspecific disfunction.

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.

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.

Identification of a consistent pattern of mutations in neurovirulent variants derived from the sabin vaccine strain of poliovirus type 2

Complete nucleotide sequencing of the RNAs of two unrelated neurovirulent isolates of Sabin-related poliovirus type 2 revealed that two nucleotides and one amino acid (amino acid 143 in the major capsid protein VP1) consistently departed from the sequences of the nonneurovirulent poliovirus type 2 712 and Sabin vaccine strains. This pattern of mutation appeared to be a feature common to all neurovirulent variants of poliovirus type 2.

Activities and mechanisms of action of halogen-substituted flavanoids against poliovirus type 2 infection in vitro

The effects of some halogen-substituted flavanoids (dichloroflavan, halogenated isoflavans, and isoflavenes) on poliovirus type 2 infection was examined. Only two isoflavenes exhibited a significant inhibitory activity on the virus-induced cytopathic effect and plaque formation. In a single cycle of viral replication, both compounds reduced the viral yield by approximately 90%. The presence of the isoflavenes from the beginning of infection or during the adsorption period only prevented the shutoff of host translation and viral RNA and protein synthesis, suggesting that the drugs blocked an early step of viral replication. Indeed, both isoflavenes were not virucidal, did not protect virus infectivity from heat inactivation, and had no measurable effect on the binding of virus to cells, viral penetration, and uncoating of the viral RNA. In contrast, both compounds significantly reduced the infectivity of free viral RNA. The possibility that compounds interfere with poliovirus replication at a very early stage of translation of the input RNA is discussed.