Minor oral surgical procedures in patients on oral anticoagulants--a controlled study.

BACKGROUND: Patients on therapeutic anticoagulation are at risk of bleeding from minor oral surgical sites. When the anticoagulant regime is modified to prevent the risk of bleeding, this at the same time predisposes the patient to risks of the medical condition for which they are being treated. METHODS: A total of 70 patients who were on warfarin treatment requiring minor oral surgical procedures were treated in the Oral Surgery Department. A control group of 35 had their warfarin stopped prior to the minor oral surgical procedure. The other 35 formed the study group. Patients with an International Normalized Ratio outside the therapeutic range of 2-4, or with history of liver disease or on drugs affecting liver function were excluded from the study. Any incidences of post-operative bleeding were recorded. RESULTS: None of the patients in either control or study group had any serious bleeding complications. CONCLUSION: The data suggest that patients can safely undergo routine minor oral surgical procedures without alterations of their therapeutic anticoagulation regime.

Regulation of protamine gene expression in an in vitro homologous system.

An in vitro transcription system from the trout testis nuclei was developed to study trout protamine gene expression. The protamine promoter contains, among others, two regulatory elements: 1) a cAMP-responsive element or CRE element (TGACGTCA) which is present in position 5' to TATA box, and 2) GC box (CCGCCC) which is present in position 3' to TATA box. The removal of the CRE-binding protein by titration (by the addition of appropriate oligonucleotides to the incubation mixture) resulted in a decrease in transcription of the protamine gene. These results were confirmed by experiments in which the pure CRE-binding factor (TPBP1) was used, as well as by those where a stimulatory effect of cAMP on protamine promoter transcription was observed. On the other hand, addition of oligonucleotides containing the GC-box sequence enhanced the protamine gene transcription indicating that the protein (Sp1 like) which binds to this sequence acts as a repressor of protamine gene expression. These results confirm the previously proposed model which suggested that the GC box played a role in negative regulation of the protamine gene expression. Involvement of some other factors in this process was also discussed.

Selective action of 4'-azidothymidine triphosphate on reverse transcriptase of human immunodeficiency virus type 1 and human DNA polymerases alpha and beta.

4'-Azidothymidine (ADRT) is a novel nucleoside analogue that exhibits potent inhibitory activity against the replication of human immunodeficiency virus (HIV) in lymphocytes. The mechanisms by which ADRT inhibits HIV reverse transcriptase (HIV-RT) as ADRT 5'-triphosphate (ADRT-TP), the active intracellular metabolite of ADRT, and as the ADRT-MP molecule incorporated into DNA were examined and compared to their effects on human DNA polymerases alpha and beta. Inhibition of HIV-RT by ADRT-TP is competitive against TTP and is more potent against RNA to DNA synthesis (Ki = 0.009 microM versus Km = 3.3 microM for TTP) than it is against DNA to DNA synthesis (Ki = 0.95 microM versus Km = 16.3 microM for TTP). ADRT-TP is also a more potent inhibitor for primer elongation on RNA template than on DNA template. ADRT-TP is a poor inhibitor of human DNA polymerases alpha (Ki = 62.5 microM) and beta (Ki = 150 microM) (Chen et al., 1992). The consequences of ADRT incorporation into DNA are strikingly different for the HIV-RT and for human DNA polymerases alpha and beta. DNA polymerases alpha and beta incorporate a single ADRT-MP molecule into nascent DNA at a very slow rate and continue to elongate. They are unable to incorporate a second consecutive ADRT-MP. However, HIV-RT is able to efficiently incorporate two consecutive ADRT molecules. Incorporation of two consecutive ADRT-MP molecules by HIV-RT prevents further DNA chain elongation. Incorporation of two ADRT-MP molecules separated by one deoxyribonucleoside monophosphate (dAMP, dCMP, or dGMP) also abolishes DNA chain elongation by HIV-RT.

Transiently and stably introduced CCAAT/enhancer-binding-protein genes are constitutively expressed in cultured cells.

CCAAT/enhancer-binding protein (C/EBP) is expressed in certain cell types including hepatocytes and adipocytes. In order to understand the mechanisms that control the expression of the mouse C/EBP gene in the liver as well as in adipocytes, we have studied both the endogenous gene and transfected C/EBP gene constructs. The initiation site of transcription was identified and a strong liver-specific DNase-I hypersensitive site located at -3 kb, which does not appear to contribute functionally to the regulation of the gene in a variety of either transiently or stably transfected cells with constructs which include sequences up to 6-kb upstream of the transcription start. C/EBP gene expression during the transition from preadipocytes to adipocytes was shown to be controlled at the level of transcription. However, adipocytes stably transfected with constructs that include -3.3 kb upstream of the C/EBP gene do not express the reporter genes in a differentiation-specific manner. We detected several DNA-binding proteins that interact with the upstream sites of the C/EBP gene. Those include two labile and two heat-stable site-specific DNA-binding proteins that are present in nuclear extracts from several tissues and cultured cell lines.

First expression of protamine message in trout testis.

In situ hybridizations were performed using a biotinylated riboprobe complementary to protamine messenger RNA in order to directly examine the various cell types in the trout testis for the presence of protamine message. Computer-aided optical density measurements were used to provide estimates of transcript abundance for cells identified by their DAPI-labeled nuclei. Optically detectable protamine hybridization occurred only in spermatid cells. These findings are in accord with results obtained in other species which report protamine mRNA only in the post-meiotic spermatid cell; but they are in conflict with a previous study employing solution hybridization which noted that protamine message first appears in the spermatocytes of rainbow trout.

Binding of nuclear proteins to the rat liver S14 gene is influenced by thyroid state.

The rat hepatic S14 gene is regulated by L-triiodothyronine (T3) and codes for a cytosolic protein (pI 4.9 and Mr 17,010) that is believed to be involved in lipogenesis. Recent studies have identified at least five DNase I hypersensitive sites (HS 1-5) in hepatic chromatin flanking the 5' region of the gene. The HS-1 site is situated immediately adjacent to the transcription initiation site. We have isolated a DNA fragment (USS-1) which contains a portion of the HS-1 site to examine the binding of nuclear proteins to S14 DNA. DNase I footprinting studies demonstrated that material extracted from hepatic nuclei with 0.42 M NaCl contained proteinase K-sensitive factors (presumed to be proteins), which bind to USS-1 DNA between positions -63 and -48 (PS-1) relative to the transcription initiation site. Examination of the binding activity with a synthetic oligonucleotide identical to the protected sequence indicated the formation of at least three protein-DNA complexes. The DNA binding activity of the PS-1 binding protein or proteins correlated with the T3 regulated expression of mRNA-S14. Although the nucleotide sequence of PS-1 closely resembles the binding site for the CCAAT transcription factor (CTF/NF-1), competition studies attempting to displace protein binding from the PS-1 sequence with DNA fragments containing the CTF/NF-1 binding motif were unsuccessful. In vitro transcriptional assay studies suggested that the DNA fragment (-441 to -2) containing the PS-1 site promotes the transcription of the S14 gene in an orientation fashion. The in vitro transcriptional activity of the S14 DNA containing the PS-1 sequence was significantly higher in hepatonuclear extracts from hyperthyroid compared with euthyroid or hypothyroid animals. In summary, our findings indicate that the DNA binding activity of proteins which bind to PS-1 site is influenced by the thyroid status of the animal.

Molecular probes for general testicular and specific spermatogenic function.

Northern analysis of human testis poly(A+) RNA with a mixture of oligonucleotide primer extended cDNA probes revealed several similar RNAs. These RNAs were subsequently cloned into a VPCS (vector-primer-cloner-sequencer) plasmid. One of these clones, NDHu1, was represented within the library a number of times and hybridized strongly to a poly(A+) RNA of congruent to 1.2 kb. Sequence analysis identified this clone as the URF 1 subunit of the mitochondrial NADH dehydrogenase (NDHu1). Comparison of the relative levels of the NDHu1 and human protamine 1 (HP1) transcripts revealed that HP1 was less abundant than NDHu1. This was unexpected, since it is known that within differentiating mammalian spermatid cells, protamine (HP1) is an abundant transcript. This suggested that the ratio of the relative levels of these two very different mRNAs was indicative of the relationship between specific spermatogenic function (germ cell transcription, determined by the level of the HP1 transcript) and general testicular cell function (determined by the level of the mitochondrial mRNAs, i.e. NDHu1). This correlation was maintained when several individuals expressing various degrees of testicular dysfunction were examined. This study suggests that these probes may be useful markers for general testicular and specific spermatogenic function.

Serum concentrations of amoxycillin in children following an oral loading dose prior to general anaesthesia: relevance for the prophylaxis of infective endocarditis.

A Working Party of the British Society for Antimicrobial Chemotherapy has recommended an oral regimen for adult patients at risk from infective endocarditis who require dental treatment under a general anaesthesia. The Working Party recommends oral amoxycillin 3 g 4 hours prior to general anaesthesia. This study shows that doses of amoxycillin previously recommended for the prophylaxis of infective endocarditis in children having treatment under local anaesthesia also result in adequate serum concentrations at the time of operation (14.34 mg/l +/- (1 S.D.) 8.64).

A vector-primer-cloner-sequencer plasmid for the construction of cDNA libraries: evidence for a rat glyceraldehyde-3-phosphate dehydrogenase-like mRNA and a ferritin mRNA within testis.

We have developed a vector-primer-cloner-sequencer (VPCS), based on the pUC plasmids, which is easy to prepare. Stable cDNA libraries have been generated from human, rat, and bull testis. The inserts are of various size classes, including high-molecular-weight reverse transcripts which can be easily sequenced. The utility of this VPCS has been demonstrated by isolating a rat ferritin and glyceraldehyde-3-phosphate dehydrogenase-like clone.

Serum amoxycillin levels following oral loading dose prior to outpatient general anaesthesia for dental extractions.

Serum amoxycillin levels were measured 4 h after oral administration of a 3 g loading dose given prior to outpatient dental treatment under general anesthesia. A mean level of 8.49 mg/l +/- (1 S.D.) 5.07 mg/l of amoxycillin was obtained, which is adequate at the time of bacteraemia to protect patients susceptible to bacterial endocarditis. A second identical dose of amoxycillin was given following recovery from anaesthesia (mean 18.7 min) and was tolerated by 97.6% of patients.