Transmission of viruses via contact in ahousehold setting: experiments using bacteriophage straight phiX174 as a model virus.

Contamination of the environment with pathogens is the prerequisite for contact infections. The aim of this study was to elucidate how viruses can be transmitted from a primary contact person to further individuals. Bacteriophage straight phiX174 was chosen as a model virus. In its stability straight phiX174 is comparable with the most resistant human pathogenic viruses, e.g. polio- or parvoviruses. About 10(7)pfu were applied to exposed contact points such as door handles or the hands of volunteers. After touching of these handles and common social contacts like hand shaking, re-isolation rates were determined from the hands of our test persons. Contaminated door handles and skin surfaces were found to be efficient sources for potential infection. At least 14 persons could be contaminated by horizontal spread, one after the other by touching the same door handle. Successive transmission from one person to another could be followed up to the sixth contact person. These results were confirmed under everyday life conditions in a flat shared by four students. The transmission could not be prevented by the usual standards of hand hygiene, practised in this household. straight phiX174 could be reisolated after 24h from the hands of all persons tested even after normal use and cleaning of their hands. This might be improved by the use of liquid soap dispensers.

Subclinical reactivation of herpes simplex virus type 1 in the oral cavity.

Reactivation in the oral cavity either symptomatically (recrudescence) or without symptoms (recurrence) may contribute to the transmission of herpes simplex virus type 1 (HSV-1), especially in critical areas of exposure such as dentistry. In order to measure the frequency of HSV-1 reactivation, nested polymerase chain reaction (PCR) was performed on oral swabs collected from 30 healthy people over a period of 58-161 days. In total 19 of 25 (76%) seropositive people were PCR-positive at least once, 6 of these 19 (32%) had recrudescence and 13 (68%) had only asymptomatic reactivation. Frequencies of additional recurrences were higher in people showing symptomatic reactivation than in those who had only recurrences. Recrudescence is a risk factor for elevated levels of asymptomatic HSV-shedding. In most cases HSV-1 was detected only by nested PCR investigated by early onset of therapy or time span before sampling.

Acyclovir treatment prevents varicella-zoster virus replication in PBMC during viremia.

The most effective antiviral therapy of varicella and zoster has become acyclovir. Using polymerase chain reaction specific for VZV ORF 14, ORF 29, ORF 63 as well as nucleic acid sequence-based amplification (ORF 63, ORF 68) we tested PBMC of patients with VZV-associated diseases for the presence of viral DNA and RNA, respectively. In PBMC of patients treated with acyclovir neither DNA nor RNA was detectable already one day after the onset of therapy. In three blood sample pairs from zoster patients we were able to detect viral nucleic acid before but not after acyclovir treatment. These results confirm clinical and epidemiological data. It can be concluded that treatment with acyclovir prevents VZV replication in peripheral blood mononuclear cells.

Determinants of stent restenosis in chronic coronary occlusions assessed by intracoronary ultrasound.

Chronic coronary occlusions have a high recurrence rate that can be reduced by stenting, but this rate remains higher than in nonocclusive lesions. To analyze possible determinants of restenosis in these lesions, intracoronary ultrasound was performed during the recanalization procedure. A chronic coronary occlusion of > or = 1 month duration (range 1 to 33 months; median 3.3) was successfully recanalized in 41 patients. Quantitative ultrasound analysis was performed before and after stent placement, with measurement of the luminal area, the extent of the plaque burden at the site proximal and distal to the occlusion, and within the occlusion and the subsequent stent. The degree of compensatory enlargement of the coronary artery within the occlusion was determined by comparing the average of the total vessel area of the proximal and distal reference with the lesion site. Early reocclusion (subacute stent thrombosis) was observed in 1 patient (2.4%). The angiographic control after 6 months showed restenosis in 9 patients with 1 late reocclusion. The overall recurrence rate was 24%. There was no difference in clinical and procedural characteristics between lesions with restenosis and without restenosis. The latter had a larger minimum stent area (7.59 +/- 1.96 mm2 vs 5.71 +/- 0.90 mm2; p <0.01), and there was evidence for more compensatory vessel enlargement in lesions without restenosis. Thus, intracoronary ultrasound showed that a smaller minimum stent area was a major predictor of angiographic restenosis, and it occurred more often in occlusions without compensatory vessel enlargement.

No acute varicella-zoster virus replication in peripheral blood mononuclear cells during postherpetic neuralgia.

Patients suffering from postherpetic neuralgia (PHN) were investigated whether varicella-zoster virus (VZV) DNA or RNA could be detected in their peripheral blood mononuclear cells (PBMCs). Altogether 16 samples were tested by standard polymerase chain reaction (PCR) for open reading frame (ORF) 14 and ORF 29, standard and nested PCR for ORF 63, and isothermal transcription-based nucleic acid amplification (NASBA) for ORF 63 and ORF 68. By these methods neither VZV DNA nor VZV RNA could be detected. The obtained results are in contrast to those of other authors (Vafai et al., 1988; Mahalingam et al., 1995) but support the hypothesis of Bennett (1994) and Kost and Straus (1996) proposing that PHN is not caused by acute VZV replication but a consequence of neuronal damage accompanying replication of VZV in ganglia during zoster episodes.

Subclinical reactivation of varicella-zoster virus in immunocompromised and immunocompetent individuals.

The occurrence of subclinical reactivation of varicella-zoster virus (VZV) in peripheral blood mononuclear cells (PBMC) from immunocompetent subjects >60 years old without any signs of VZV-caused illnesses, and from immunocompromised patients was investigated. Altogether, 223 samples were tested by nested ORF 63 PCR assay. In addition, all positive samples were tested by ORF 14, ORF 29 and ORF 63 PCR assays, as well as by ORF 63 and ORF 68 nucleic acid sequence-based amplification assays. In 5 samples, VZV-specific DNA, but no transcripts, could be detected. Three of them belonged to the group of >60-year-olds, 1 was HIV positive, the other was being treated with chemotherapy. The results confirm the observation of other authors that subclinical reactivation occurs in both immunocompromised and healthy individuals. The failure to detect DNA in samples taken from 2 individuals several weeks later excludes a long-lasting infection of VZV in PBMC.

Additional luminal area gain by intravascular ultrasound guidance after coronary stent implantation with high inflation pressure.

AIMS: Studies by intravascular ultrasound demonstrated inadequate expansion in a large number of stents, which lead to the increase of inflation pressure for stenting. The present study examined whether routine use of high-pressure inflation would be sufficient for an optimum stent expansion without sonographic guidance. METHODS AND RESULTS: Two types of single coronary stents (Palmaz-Schatz in 54, and Wiktor in 25) were implanted with inflation pressures of 16-20 atm in 79 nonocclusive coronary lesions. IVUS before stenting was used in 78% to select the adequate stent size. Intravascular ultrasound after stenting was used to asses the minimum stent are and diameter, the reference areas, and the strut apposition to the vessel wall. The difference between the area of the expanding balloon and the stent area was calculated as the luminal deficit of the stent. Completeness of stent expansion required full strut apposition and lesion coverage, and a minimum stent area that was larger than the distal reference, and larger than 60% of the proximal reference. Intravascular ultrasound before stenting lead to an increase of the stent size in 47%. After high-pressure expansion, even with the optimized balloon size, 8% of stents had struts protruding into the lumen. The stent area (6.87 +/- 1.93 mm2) was significantly smaller than both the proximal (9.59 +/- 2.91 mm2; p < 0.001) and distal reference area (8.23 +/- 3.03 mm2; p < 0.001). The criteria for complete expansion were met in 48%. The expansion with a larger high-pressure balloon in 28 stents lead to an increase of the stent area by 19% (8.19 +/- 2.24; p < 0.001), and full stent apposition in all cases. The criteria of stent expansion were met in 82%. A wide range of the luminal deficit upto 48% was observed, which was not related to sonographic lesion characteristics, except in lesions with complete circumferential calcifications. The different stent designs were characterized by a slightly lower luminal deficit in slotted-tube stents (23 +/- 13% vs. 28 +/- 12%; p = 0.11) and a better index of stent symmetry as compared with the coil stent (0.87 +/- 0.08 vs. 0.82 +/- 0.09; p < 0.05). CONCLUSION: Routine use of high-pressure stent expansion did not lead to a sufficient stent expansion, even when the initial stent size had been guided by intravascular ultrasound. Further stent dilatation with larger balloons under ultrasound guidance would be required to optimize the luminal area gain.

[Embolic complications in bacterial endocarditis]. / Embolische Komplikationen bei bakterieller Endokarditis.

Embolic complications are a major prognostic determinant in the clinical course of infective endocarditis (IE) with an incidence of about 30-50%. In order to analyze risk factors leading to embolism in native (NVE) and prosthetic valve endocarditis (PVE), we reviewed 177 consecutive patients; 43% were female, 57% male, PVE occurred in 24% of all patients all left-sided, among the NVE were 11% right-sided IE. Major embolic complications occurred in 40% of all patients. In NVE, a higher rate of embolic events (45% vs. 26%; p < 0.05), and a larger vegetation size compared to PVE was observed (14 +/- 6 mm vs. 11 +/- 5 mm; p < 0.05). The most important risk factor for embolic complications in NVE was Staphylococcus aureus (odds ratio 6.4). Furthermore, double valve endocarditis, fever, and mitral valve endocarditis were associated with the risk for embolism. In case of severe regurgitation the rate of embolic complications was reduced (54% vs. 77%; p < 0.05). In PVE, fever was a risk factor for embolic events. Staphylococcus aureus was also a frequent microorganism in embolism (45% vs. 22%). The in-hospital mortality was significantly increased in case of embolism (NVE 40% vs. 11%; p < 0.001; PVE 36% vs. 9% p < 0.05). About 50% of all embolic events occurred before admission. In NVE, due to high in-hospital mortality, the rate of patients with embolism undergoing surgery was lower (57% vs. 72%; p < 0.05); whereas in PVE no significant difference was observed. In patients with NVE, aspirin therapy because of coronary artery disease appeared to reduce the rate of embolic complications (11% vs. 47%). However, the low number of patients on aspirin (9%) does not allow recommendations regarding a potential benefit. In conclusion, identification of risk factors leading to embolism in IE may be useful in considering early surgical therapy. However, the high rate of embolic complications before hospital admission indicates a need for improving the diagnostic delay in the prehospital phase.

Survival of phage M13 with uracils on one or both DNA strands.

The survival of M13 DNA was studied after partial replacement of thymine by uracil in the bacteriophage. Uracils carry the same genetic information as the thymines. Nevertheless in Escherichia coli wild-type cells, uracils in DNA are replaced by thymines by excision repair initiated by uracil-DNA glycosylase (UDG). Thus inactivation of uracil-containing phage DNA is solely due to repair initiated by UDG. Incorporation of uracils was achieved in one or in both strands, either randomly or site-specifically using differently uracylated oligonucleotides. The results show that up to 580 uracils can be repaired without a significant decrease in survival if the uracils are localized in the (-) strand only. Incorporation of 246 uracils into the (+) strand leads to approximately 30% or approximately 10% survival when expressed in Escherichia coli strains CMK and JM103, respectively. However, when uracils are distributed over both strands a sharp decrease in survival occurs. This shows that the repair of two uracils localized in close proximity on opposite strands of the DNA by the excision repair mechanism is difficult, whereas uracils occurring in one strand are repaired more efficiently, irrespective of their number.

The "additional subunit" CF0II of the photosynthetic ATP-synthase and the thylakoid polypeptide, binding ferredoxin NADP reductase: are they different?

Evidence is presented to support the notion that the 16 kDa thylakoid polypeptide, called CF0II, is an essential subunit of the photosynthetic ATP-synthase complex CF0CF1: It is co-isolated with the other subunits of CF0CF1 in preparations either using octylglucoside/cholate or Triton X-100. It is co-precipitated by antibodies together with the other CF0CF1 subunits. It is immunochemically not related to thylakoid polypeptides of higher molecular weight nor to some thylakoid polypeptides with similar apparent molecular weight between 16 and 18 kDa: CF1 epsilon, CF0I, subunit IV of the b6f complex, the 16.5 kDa peripheral polypeptide of the oxygen evolving complex of PS II, and the intrinsic ferredoxin NADP reductase binding protein. The N-terminal amino acid sequences of CF0II and the reductase binding protein is determined by Edman degradation and compared: The two sequences are different and not identical to other characterized thylakoid polypeptides. Monospecific antibodies against CF0II inhibit rebinding of CF1 to EDTA treated thylakoid membranes, H+ efflux from EDTA treated membranes and cyclic photophosphorylation. Thus the additional polypeptide CF0II qualifies for a functional subunit of the photosynthetic ATP-synthase.