Selective hydrogenolysis of novel benzyl carbamate protecting groups.

[formula: see text] Highly efficient and selective hydrogenolysis of the 2-naphthylmethyl carbamate group (CNAP) in the presence of the 4-trifluoromethylbenzyl carbamate group (CTFB) has been observed for a wide range of substrates.

Transcranial Doppler: preventing stroke during carotid endarterectomy.

Carotid endarterectomy (CEA) is more effective at preventing strokes than medical therapy alone in those patients with severe symptomatic stenosis of the internal carotid artery and this benefit persists despite a perioperative stroke/death rate of approximately 5%. Thromboembolism has been established as the underlying cause of the majority of perioperative strokes, but this could not be detected using the existing methods of monitoring or quality control. Early studies demonstrated that transcranial Doppler monitoring (TCD) could detect intraoperative embolism, but the clinical significance of this finding was questioned as the incidence of these emboli far exceeded the incidence of perioperative strokes.

A policy of quality control assessment helps to reduce the risk of intraoperative stroke during carotid endarterectomy.

Objectives: A pilot study in our unit suggested that a combination of transcranial Doppler (TCD) plus completion angioscopy reduced incidence of intra-operative stroke (i.e. patients recovering from anaesthesia with a new deficit) during carotid endarterectomy (CEA).

The epidemiology of louping-ill, a tick borne infection of red grouse (Lagopus lagopus scoticus).

The epidemiology of louping-ill in red grouse was studied in northern Britain concentrating on the possible role of other species and mechanisms of disease persistence. This tick borne viral disease caused heavy mortality in red grouse, particularly chicks. Louping-ill induced mortality reduced the strength of the density dependence that generates the tendency of grouse populations to cycle and in some populations may cause population sinks.

The effect of perioperative embolisation on visual function in patients undergoing carotid endarterectomy.

Objectives: To investigate the effect of carotid artery embolisation detected by transcranial Doppler (TCD) monitoring during carotid endarterectomy (CEA) on visual function.

Design: A prospective study. Visual function was assessed by an independent ophthalmalogist.

Experience with transcranial Doppler monitoring reduces the incidence of particulate embolization during carotid endarterectomy.

Background: The aim of this study was to investigate whether the introduction of routine transcranial Doppler (TCD) ultrasonography during carotid endarterectomy reduces the incidence of microembolization by altering operative technique.

Methods: The number and nature of microemboli detected during the first 75 consecutive carotid endarterectomies performed with TCD monitoring during 1992-1993 (group 1) were compared with those in a similar series of 75 consecutive patients undergoing carotid endarterectomy in 1995 (group 2), after substantial experience (210 patients) with TCD monitoring. Emboli were classified as either particulate or gaseous.

Secondary structure of the 3'-untranslated region of yellow fever virus: implications for virulence, attenuation and vaccine development.

A genetic algorithm-based RNA secondary structure prediction was combined with comparative sequence analysis to construct models of folding for the distal 380 nucleotides of the 3'-untranslated region (3'-UTR) of yellow fever virus (YFV). A number of structural elements that are thermodynamically stable, conserved in shape, and confirmed by compensatory mutations were revealed. At the same time structural polymorphisms were observed among strains of YFV.

Transmission of louping ill virus between infected and uninfected ticks co-feeding on mountain hares.

Most of the data on oral infection of ticks by louping ill virus have been obtained from experiments in which animals were infected by syringe inoculation with infectious material. Using infected ticks to mimic the natural situation, we have demonstrated that louping ill (LI) virus transmission can occur from infected to uninfected Ixodes ricinus feeding in close proximity on mountain hares (Lepus timidus). Under these conditions the hares developed either low or undetectable viraemias.

Definitive identification of louping ill virus by RT-PCR and sequencing in field populations of Ixodes ricinus on the Lochindorb estate.

Rapid and precise virus detection procedures are an important component of any epizootiological study. An automated one tube reverse transcriptase and nested primer polymerase chain reaction (RT-PCR) followed by nucleotide sequencing of the cDNA product, was used for the rapid detection and identification of louping ill (LI) virus in field caught Ixodes ricinus and compared with a classical isolation method i.e.

Quality control during carotid endarterectomy.

Although some form of quality control assessment is standard practice following virtually all forms of peripheral vascular reconstruction, it is seldom applied to carotid endarterectomy. This is despite the fact that the complications following endarterectomy can be catastrophic, are often related to technical error and are not easily remedied. A number of novel quality control techniques are now available.

Unstable carotid plaques: preoperative identification and association with intraoperative embolisation detected by transcranial Doppler.

Objectives: To investigate whether unstable carotid plaque characteristics, as determined by preoperative colour Duplex ultrasonography (CDU) and postoperative histological examination, were associated with particulate embolisation, detected by transcranial Doppler (TCD), during the initial dissection of the carotid bifurcation during carotid endarterectomy(CEA).

Design: A prospective, consecutive study was undertaken of 50 patients undergoing carotid endarterectomy(CEA).

Setting: Leicester Royal Infirmary, Leicester, U.

A comparison of quality control methods applied to carotid endarterectomy.

Objectives: To compare the ability of continuous wave Doppler (CWD), B-mode ultrasound (BMU), angioscopy and transcranial Doppler (TCD) to detect technical error during carotid endarterectomy (CEA).

Design: A prospective, comparative study in 100 consecutive patients.

Setting: Leicester Royal Infirmary, Leicester, U.

Interpretation of embolic phenomena during carotid endarterectomy.

Background And Purpose: Air and particulate emboli are a major source of morbidity during carotid endarterectomy (CEA); however, amplitude overload and poor time resolution have restricted the ability of transcranial Doppler ultrasound to differentiate between the two.

Methods: We have now overcome these two limitations by (1) rerouting embolic signals away from the audio frequency amplifier to avoid amplitude overload and (2) substituting the Wigner distribution function for the fast Fourier transform to improve time and frequency resolution. Thus, we can now accurately determine embolic duration and embolic velocity, the product of which is the sample volume length (SVL).

E461H-beta-galactosidase (Escherichia coli): altered divalent metal specificity and slow but reversible metal inactivation.

beta-galactosidase (Escherichia coli) with a His substituted for Glu-461 retained about 10% of its normal activity in the absence of divalent metals but was inactivated rather than activated by Mg2+, Mn2+, Zn2+, Ni2+, Cu2+, and Co2+. Since Zn2+, Ni2+, Cu2+, and Co2+ do not interact with wild type beta-galactosidase while Mg2+ and Mn2+ activate and Ca2+ binds but has no effect on wild type beta-galactosidase activity, the substituted enzyme has very different divalent metal interactions. A much larger amount of Mg2+ than of the other divalent metal ions was needed to inactivate the substituted enzyme at pH 7 (half-maximal activity was at 12.

Assessment of intracranial primary collaterals using transcranial color-coded real-time sonography.

Transcranial color-coded sonography (TCCS) was used to assess primary willisian collaterals in 100 patients with extracranial internal carotid artery (ICA) stenosis. Their importance was determined during carotid endarterectomy (CEA) by transcranial Doppler measurement of blood flow velocity in the ipsilateral middle cerebral artery (MCAV) before and after carotid clamping. All patients had unilateral ICA disease of at least 60% stenosis.

Persistence and transmission of tick-borne viruses: Ixodes ricinus and louping-ill virus in red grouse populations.

The population dynamics of tick-borne disease agents and in particular the mechanisms which influence their persistence are examined with reference to the flavivirus that causes louping-ill in red grouse and sheep. Pockets of infection cause heavy mortality and the infection probably persists as a consequence of immigration of susceptible hosts. Seroprevalence is positively associated with temporal variations in vectors per host, although variation between areas is associated with the abundance of mountain hares.

Clinical relevance of intraoperative embolization detected by transcranial Doppler ultrasonography during carotid endarterectomy: a prospective study of 100 patients.

A study was performed to investigate the clinical significance of microembolization detected by transcranial Doppler ultrasonography (TCD) by determining the quantity and character of emboli and correlating these with neurological and psychometric outcome, fundoscopy, automated visual field testing and computed tomographic brain scans in 100 consecutive patients undergoing carotid endarterectomy. Embolization was detected in 92 per cent of successfully monitored operations. Most emboli were characteristic of air and not associated with adverse clinical outcome.

On-table diagnosis of incipient carotid artery thrombosis during carotid endarterectomy by transcranial Doppler scanning.

We present a case where transcranial Doppler ultrasound monitoring of a carotid endarterectomy enabled us to detect the incipient thrombosis of the operated artery before reversal of anesthesia. The use of transcranial Doppler ultrasound monitoring in carotid endarterectomy has the potential to detect this complication before serious neurologic damage has occurred and therefore reduce the morbidity and mortality rates associated with the operation.