4D Flow analysis of intracavitary blood flow dynamics and energetics in the systemic right ventricle

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Italian Ministry of Health

Background

The systemic position of a morphologically right ventricle (SRV) makes it vulnerable to fail, leading to high incidence of heart failure and cardiac death [1]. Understanding SRV intracavitary blood flow dynamics and energetics could improve patient risk stratification.

Purpose

Testing the potential of three-dimensional time-resolved phase contrast cardiac magnetic resonance (4D Flow) in quantifying SRV blood flow dynamics and energetics.

Methods

4D Flow prototype sequences were acquired on 3 patients (1 male, 2 females) with SRV in D-loop transposition of great arteries after atrial switch operation (D-TGA/ASO), 3 male patients with SRV in L-loop TGA (L-TGA) and healthy controls (2 males, 1 female).

Kinetic energy (KE), viscous energy loss (EL), dissipation index (DI) calculated as EL to KE ratio, and hemodynamics forces (HFs) resulting from pressure gradients, were computed for the D-TGA/ASO and L-TGA SRVs, and for the control left ventricles (LVs) and right ventricles (RVs). HFs were decomposed in inferior-anterior, septal-lateral and basal-apical components (HFIA, HFSL, HFBA, respectively)

Results

Figure 1 reports the time-course of HF components and the general features of the enrolled subjects.

In systole, all SRVs (Figure 1a-1b) presented a dominant HFIA and a minor HFSL, similarly to RVs (Figure 1c); however, HFSL had a positive peak, indicating septal contraction towards the SRV cavity, opposite to its normal motion. HFBA magnitude was similar to LVs (Figure 1d), suggesting that the shortening of the tricuspid anulus towards the apex is more pronounced than in RVs (Figure 1c).

Over the whole cardiac cycle, DI values were highest in D-TGA/ASO SVRs (0.40-0.55); in L-TGA SRVs, DI values (0.24-0.45) were comparable to healthy LVs (0.22-0.37) and RVs (0.23-0.36). This difference may be related to the fact that in DTGA/ASO the left atrium is functionally replaced by a pulmonary venous baffle, which lacks efficient contraction, as highlighted by the absence of a distinctive A-wave in the KE time-course (Figure 2a).

Due to the adaptation to systemic afterload, SRVs were hypertrophic (Figure 1a-1b), with indexed mass higher than normal RVs (Figure 1c), and presented reduced compliance to the diastolic filling, as suggested by increased KE E-wave slope in L-TGA (Figure 2b) compared to controls (Figure 2c-2d).

Conclusions

Intracavitary HFs in SRVs reveal a partial shift from a RV towards LV pattern. This occurs at the expenses of a higher energetic consumption in D-TGA/ASO than L-TGA, enlightening the crucial role of atrial contribution to impaired SRV diastolic filling. These findings corroborate the previous evidence that patients with D-TGA/ASO have abnormal decrease in stroke volume during exercise whereas L-TGA patients can reach values comparably to healthy controls [2].

Assessment of left ventricular performance during laparoscopy

OBJECTIVES

Cardiovascular changes during laparoscopic surgery have been described in several studies. Pneumoperitoneum effects on cardiac performance instead have not been much investigated and are less known. The carbon dioxide insufflation necessary in order to perform laparoscopic procedures represents a higher force against which the myocardial fibers must shorten during ventricular contraction. Hypothesis of this study is that the intra-abdominal pressure at 12 mmHg could acutely affect the left ventricular wall stress and work. Aim of the study was to evaluate the impact of relationship pneumoperitoneum on the echocardiographic measures of left ventricular contractile function.

PATIENTS AND METHODS

We studied 20 healthy, ASA I women, undergoing laparoscopic hysterectomy. Transthoracic echocardiography was performed preoperatively, after induction of anaesthesia, 15' after pneumoperitoneum, 15' after Trendelenburg positioning and 15' after the end of surgery. Left ventricular end-systolic wall stress, stroke work, left ventricular ejection time and mean velocity of fiber shortening were registered.

RESULTS

Carbon dioxide insufflation caused a consistent increase in left ventricular end-systolic wall stress and left ventricular ejection time, while the mean velocity of fiber shortening decreased. The Trendelenburg position did not produce any other signficant effects. These changes were transient with a return to preinsufflation values at the last measurement. Pneumoperitoneum adversely affects left ventricular performance during laparoscopy, leading to an increase of left ventricular end-systolic wall stress and reducing the mean velocity of circumferential fiber shortening. These cardiac consequences appear to be reversible since all the echocardiographic parameters normalized at the end of surgery.

CONCLUSIONS

Our results suggest that there is an adaptation of the cardiac systolic contractile status to the pressure overload during laparoscopy.

Dopamine infusion and fluid administration improve renal function during laparoscopic surgery

BACKGROUND

Previous studies have documented the negative influence of pneumoperitoneum on cardiac and renal function during laparoscopy. In this respect, regard there is a lack of data regarding the use of an appropriate management of fluid therapy to decrease these side effects. The aim of this study was to investigate the cardiac and renal responses to the administration of different amounts of crystalloid solution, alone or in association with dopamine during laparoscopy.

METHODS

Sixty ASA I patients undergoing laparoscopic surgery for endometriosis were randomly assigned to three groups. Group A was given saline solution at 5 mL/kg/h; group B received saline solution at 5 mL/kg/h and dopamine 3 mg/kg/min, and group C received saline solution at 10 mL/kg/h. Patients received A, B or C perioperatively. Renal function was evaluated by assessing total intraoperative diuresis and estimated glomerular filtration rate. Vasopressin plasmatic levels before and after surgery were measured. Transthoracic echocardiography was performed to estimate left ventricular filling pressure by using Tissue Doppler Imaging and registering the E/Ea ratio every hour after pneumoperitoneum.

RESULTS

Total intraoperative diuresis was impaired in group A and significantly increased in group C (P<0.001). In group A estimated glomerular filtration rate significantly decreased after the end of surgery (P<0.003) and vasopressin significantly increased (P<0.001). The E/Ea ratio was significantly increased in group C (P<0.001). The infusion of saline solutions with the addition of dopamine slightly affected this parameter.

CONCLUSION

A low rate of saline infusion could lead to an impaired renal function during laparoscopic surgery. This could be prevented by increasing the amount of saline solutions infused per hour or by adding a dopamine infusion.

Short-term neurodevelopmental outcome of babies operated on for low-risk esophageal atresia: a pilot study

Data on the neurodevelopmental outcome of esophageal atresia (EA) survivors are scarce, controversial, and based on small samples. This is an observational prospective longitudinal study on a selected cohort of low-risk EA survivors. We considered a low-risk EA survivor a patient with the following characteristics: gestational age >32 weeks, no long gap, no genetic or chromosomic anomaly associated with neurodevelopmental delay, and no further major surgical congenital anomalies. Infants were evaluated with scales derived from the Bayley Scales of Infant and Toddler Development - 3rd Edition at 6 and 12 months, with a score of 100 considered normal for each scale. Analysis of variance was used to assess differences of cognitive and motor development. Linear regression was used to assess the impact of the following clinical and sociodemographic variables: gender, birthweight, gestational age, length of hospital stay, number of surgeries and number of esophageal dilatations during first hospitalization, days of mechanical ventilation, weight at follow up, number of surgeries and esophageal dilatations at follow up, parental age, educational level, and socioeconomic status. Thirty children form the object of the study. The mean (standard deviation [SD]) cognitive scale's score was 93.7 (7.5) and 98.2 (9.6) at 6 and 12 months, respectively (P < 0.05). The mean (SD) motor scale's score was 97.6 (9.3) and 98.0 (12.1) at 6 and 12 months, respectively (P = n.s.). Children with a body weight <5° percentile at 12 months showed a mean (SD) cognitive score significantly lower when compared with those with a body weight >5° percentile: 88.8 (6.3) and 100.5 (8.9), respectively. At 12 months, children with unemployed mothers had a mean (SD) motor score significantly lower when compared with those in the other socioeconomic classes: 87.7 (9.8) and 100.6 (12.4), respectively. In conclusion, parents of babies operated on for low-risk EA can be reassured about neurodevelopmental outcome at least up to 1 year of age. When offering a multidisciplinary follow-up program, underweight patients should deserve particular attention to promote their quality of life and support their global development.

Desflurane versus sevoflurane: a comparison on stress response

BACKGROUND

Neurohumoral, immunologic and metabolic alteration characterize surgical procedures in relation with the intensity of injury, the total operating time and the anesthetic technique. We, therefore, compared the effects of desflurane versus sevoflurane anesthesia on intra and postoperative release of the stress hormones and inflammatory cytokines.

METHODS

Fifty Caucasian women undergoing laparoscopic surgery for benign ovarian cysts were randomized to receive inhaled anesthesia with desflurane (DES group; N.=25) or sevoflurane (SEVO group; N.=25), with fentanyl bolus and remifentanil infusion. Plasma levels of noradrenaline, adrenaline, ACTH and cortisol were measured preoperatively (T1), 30 minutes after the beginning of surgery (T2), and 30 minutes, 2 and 4 hours after the end of surgery (T3, T4, T5 respectively). Interleukin 6 (IL-6), glucose and C-reactive protein (CRP) were measured at T1, T2,T3, T4, T5 and 12 hours after the end of surgery (T6).

RESULTS

An increase of catecholamines during (T2) and immediately after surgery (T3) was observed in both groups. However, adrenaline and noradrenaline levels were significantly higher in the DES group compared to the SEVO group. Despite a drop of cortisol concentration was observed in both groups, only in the DES group there was a significant difference intraoperatively as compared to the baseline levels and to the SEVO group. While, the consequent increase of ACTH was significantly higher in the SEVO group at T2-T4. The preoperatory levels were restored at T5. Glucose, IL-6, CRP levels and postoperative pain did not show significant differences in timing within the same group and comparing DES vs SEVO group.

CONCLUSION

In the present study we demonstrated that desflurane and sevoflurane produced a different stress response in the setting of laparoscopic surgery. The greater release of catecholamines during desflurane anesthesia could have adverse effects in patients with pre-existing cardiovascular disease. In low stress surgery desflurane, as compared to sevoflurane, was associated with a better control of intraoperative cortisol and ACTH response (T2). Moreover, the ACTH secretion resulted attenuated also postoperatively (T3-T4). Both gases did not influence the plasmatic levels of Il-6, CRP and glucose.

Efficacy of scheduled time ketorolac administration compared to continuous infusion for post-operative pain after abdominal surgery

BACKGROUND

Ketorolac tromethanime is a non steroidal anti inflammatory drug and its efficacy on acute pain control after abdominal surgery has been well documented. It has a rapid onset and it can be given both for intra operative and for post operative pain management.

AIM

In this study we aimed to evaluate if there were any differences in relieving post operative pain when Ketorolac was administered with continuous infusion or if it was given at prearranged times.

PATIENTS AND METHODS

80 ASA I patients, scheduled for major gynecological surgery, were randomly assigned to 2 groups: group A patients were connected after surgical incision with a 24h analgesic infusor (2 ml/h) containing morphine (0.02 mg/kg/h) and Ketorolac (90 mg). Group B patients were connected after surgical incision with a 24h analgesic infusor (2 ml/h) containing morphine (0.02 mg/kg/h) at first and Ketorolac was then given in bolus after surgical incision and then every 8 hours for the first 24 hours. Post-operative pain scores were assessed using the Visual Analogue Scale (VAS) every 8 hours for 24 h. For a VAS value greater than 6, patients received Tramadol 100 mg.

RESULTS

Post-operative pain scores showed a better pain relief for patients in the group B. Furthermore, the requirements of rescue analgesic were less in the group B [Tramadol was used for only 8 patients] than in the group A [Tramadol was used for 31 patients]. No adverse effects were registered in both groups. <strong>

CONCLUSIONS

</strong> For post-operative pain Ketorolac administration at prearranged times, every 8 hours, offers greater benefits in respect to its continuous infusion.

Influence of pneumoperitoneum on left ventricular filling pressures and NT-proBNP levels

BACKGROUND

We recently demonstrated that pneumoperitoneum affects diastolic echocardiographic findings in healthy women scheduled for gynaecologic laparoscopy. No reports have been conducted in order to assess the echocardiographic consequences in hypertensive subjects during laparoscopic procedures.

AIM

The aim of this study was to evaluate Left Ventricular filling pressures in hypertensive women with and without diastolic dysfunction, combining the tissue Doppler imaging technique and the plasmatic levels of amino terminal proBNP.

MATERIALS AND METHODS

Doppler recordings of mitral inflow, tissue Doppler imaging of mitral annulus and N-terminal-proBNP plasmatic levels were obtained in 40 hypertensive women with or without diastolic dysfunction. Measurements were executed in awake patients (T0), after the induction of anesthesia (T1), 10 and 20 minutes after the creation of the pneumoperitoneum (T2 and T3, respectively) and at the end of the surgery (T4). Furthermore, we collected the last blood sample after 12 hours (T5).

RESULTS

The E/Ea ratio for the evaluation of left ventricular filling pressures were higher in the diastolic dysfunction group than in the non diastolic dysfunction and significantly increased after pneumoperitoneum. Pneumoperitoneum increased the plasmatic levels of natriuretic peptide in both groups. At the end of the procedure we did not observe any further significant alteration.

CONCLUSIONS

Pneumoperitoneum produces a consistent increase of ventricular filling pressures in a population of hypertensive patients with and without diastolic dysfunction. Moreover, there is a significant but transient rise in NT-proBNP after gas insufflation in both groups, most accentuated in the diastolic dysfunction group.

pRB expression in esophageal mucosa of individuals at high risk for squamous cell carcinoma of the esophagus

AIM: To investigate the pRb expression in a large group of patients with history of chronic exposure to the main risk factors for development of squamous cell carcinoma of the esophagus.

METHODS: One hundred and seventy asympto-matic individuals at high risk for esophageal squamous cell carcinoma (consumption of more than 80 g of ethanol and 10 cigarettes/d for at least 10 years) underwent upper gastrointestinal endoscopy with biopsies of the esophageal mucosa. As a control group, specimens of esophageal mucosa obtained from 20 healthy subjects were also studied. Immunohistochemical assessment of the tissues was performed using a monoclonal antibody anti-pRB protein.

RESULTS: Absence of the pRB staining, indicating loss of RB function, was observed in 33 (19.4%) of the individuals at risk for esophageal cancer, but in none of the healthy controls (P < 0.02). Loss of pRb expression increased in a stepwise fashion according to the severity of the histological findings (P < 0.005): normal mucosa (11/97 or 11.3%), chronic esophagitis (17/60 or 28.3%), low-grade dysplasia (3/10 or 30%), high-grade dysplasia 1/2 or 50%) and squamous cell carcinoma (1/1 or 100%).

CONCLUSION: Our findings suggest that abnormal expression of the pRB protein may be implicated in the process of esophageal carcinogenesis. Additional studies are warranted to define the role of the pRB protein as a biomarker for development of esophageal squamous cell carcinoma in individuals at high risk for this malignancy.

Spectroscopy enhances the information content of optical mammography

Near-infrared (NIR) diffuse optical spectroscopy and imaging may enhance existing technologies for breast cancer screening, diagnosis, and treatment. NIR techniques are based on quantitative measurements of functional contrast between healthy and diseased tissue. In this study we measured the spectral dependence of tissue absorption (mu(a)) and reduced scattering (mu'(s)) in the breasts of 30 healthy women and one woman with a fibroadenoma using a seven-wavelength frequency-domain photon migration probe. Subjects included pre- and postmenopausal women between the ages of 18 and 64. Multi-spectral measurements were used along with a four-component fit to determine the concentrations of de-oxy and oxy-hemoglobin, water and lipids in breast. The scattering spectral shape was also quantified. Our measurements demonstrate that the measured concentrations of NIR analytes correlate well with known breast physiology. Although the tissue scattering at a single wavelength was found to have little value as a functional parameter, the dependence of the scattering on wavelength provided key insights into breast composition and physiology. Lipids and scattering spectra in the breast were found to increase and decrease, respectively, with increasing body mass index. Simple calculations are also provided to demonstrate potential penalties from ignoring the contributions of water and lipids in breast measurements. Finally, water is shown to be a possible indicator for detecting a fibroadenoma, whereas the hemoglobin saturation was found to be a poor indicator. Multi-spectral measurements, compared to measurements restricted to one or two wavelengths, provide additional information that may be useful in managing breast disease.

Perturbation Monte Carlo methods to solve inverse photon migration problems in heterogeneous tissues

We introduce a novel and efficient method to provide solutions to inverse photon migration problems in heterogeneous turbid media. The method extracts derivative information from a single Monte Carlo simulation to permit the rapid determination of rates of change in the detected photon signal with respect to perturbations in background tissue optical properties. We then feed this derivative information to a nonlinear optimization algorithm to determine the optical properties of the tissue heterogeneity under examination. We demonstrate the use of this approach to solve rapidly a two-region inverse problem of photon migration in the transport regime, for which diffusion-approximation-based approaches are not applicable.

Sources of absorption and scattering contrast for near-infrared optical mammography

RATIONALE AND OBJECTIVES

Near-infrared (NIR) diffuse optical spectroscopy and imaging may enhance existing technologies for breast cancer screening, diagnosis, and treatment. NIR techniques are based on sensitive, quantitative measurements of functional contrast between healthy and diseased tissue. In this study, the authors quantified the origins of this contrast in healthy breasts.

MATERIALS AND METHODS

A seven-wavelength frequency-domain photon migration probe was used to perform noninvasive NIR measurements in the breasts of 28 healthy women, both pre- and postmenopausal, aged 18-64 years. A diffusive model of light transport quantified oxygenated and deoxygenated hemoglobin, water, and lipid by their absorption signatures. Changes in the measured light-scattering spectra were quantified by means of a "scatter power" parameter.

RESULTS

Substantial quantitative differences were observed in both absorption and scattering spectra of breast as a function of subject age. These physiologic changes were consistent with long-term hormone-dependent transformations that occur in breast. Instrument response was not adversely affected by subject age or menopausal status.

CONCLUSION

These measurements provide new insight into endogenous optical absorption and scattering contrast mechanisms and have important implications for the development of optical mammography. NIR spectroscopy yields quantitative functional information that cannot be obtained with other noninvasive radiologic techniques.

Quantifying the absorption and reduced scattering coefficients of tissuelike turbid media over a broad spectral range with noncontact Fourier-transform hyperspectral imaging

Absorption (mu(a)) and reduced scattering (mu(s)') spectra of turbid media were quantified with a noncontact imaging approach based on a Fourier-transform interferometric imaging system (FTIIS). The FTIIS was used to collect hyperspectral images of the steady-state diffuse reflectance from turbid media. Spatially resolved reflectance data from Monte Carlo simulations were fitted to the recorded hyperspectral images to quantify mu(a) and mu(s)' spectra in the 550-850-nm region. A simple and effective calibration approach was introduced to account for the instrument response. With reflectance data that were close to and far from the source (0.5-6.5 mm), mu(a) and mu(s)' of homogeneous, semi-infinite turbid phantoms with optical property ranges comparable with those of tissues were determined with an accuracy of +/-7% and +/-3%, respectively. Prediction accuracy for mu(a) and mu(s)' degraded to +/-12% and +/-4%, respectively, when only reflectance data close to the source (0.5-2.5 mm) were used. Results indicate that reflectance data close to and far from the source are necessary for optimal quantification of mu(a) and mu(s)'. The spectral properties of mu(a) and mu(s)' values were used to determine the concentrations of absorbers and scatterers, respectively. Absorber and scatterer concentrations of two-chromophore turbid media were determined with an accuracy of +/-5% and +/-3%, respectively.

Broadband absorption spectroscopy in turbid media by combined frequency-domain and steady-state methods

A technique for measuring broadband near-infrared absorption spectra of turbid media that uses a combination of frequency-domain (FD) and steady-state (SS) reflectance methods is presented. Most of the wavelength coverage is provided by a white-light SS measurement, whereas the FD data are acquired at a few selected wavelengths. Coefficients of absorption (mu(a)) and reduced scattering (mu(s)') derived from the FD data are used to calibrate the intensity of the SS measurements and to estimate mu(s)' at all wavelengths in the spectral window of interest. After these steps are performed, one can determine mu(a) by comparing the SS reflectance values with the predictions of diffusion theory, wavelength by wavelength. Absorption spectra of a turbid phantom and of human breast tissue in vivo, derived with the combined SSFD technique, agree well with expected reference values. All measurements can be performed at a single source-detector separation distance, reducing the variations in sampling volume that exist in multidistance methods. The technique uses relatively inexpensive light sources and detectors and is easily implemented on an existing multiwavelength FD system.

In vivo local determination of tissue optical properties: applications to human brain

Local and superficial near-infrared (NIR) optical-property characterization of turbid biological tissues can be achieved by measurement of spatially resolved diffuse reflectance at small source-detector separations (<1.4 mm). However, in these conditions the inverse problem, i.e., calculation of localized absorption and the reduced scattering coefficients, is necessarily sensitive to the scattering phase function. This effect can be minimized if a new parameter of the phase function gamma, which depends on the first and the second moments of the phase function, is known. If gamma is unknown, an estimation of this parameter can be obtained by the measurement, but the uncertainty of the absorption coefficient is increased. A spatially resolved reflectance probe employing multiple detector fibers (0.3-1.4 mm from the source) is described. Monte Carlo simulations are used to determine gamma, the reduced scattering and absorption coefficients from reflectance data. Probe performance is assessed by measurements on phantoms, the optical properties of which were measured by other techniques [frequency domain photon migration (FDPM) and spatially resolved transmittance]. Our results show that changes in the absorption coefficient, the reduced scattering coefficient, and gamma can be measured to within +/-0.005 mm(-1), +/-0.05 mm(-1), and +/-0.2, respectively. In vivo measurements performed intraoperatively on a human skull and brain are reported for four NIR wavelengths (674, 811, 849, 956 nm) when the spatially resolved probe and FDPM are used. The spatially resolved probe shows optimum measurement sensitivity in the measurement volume immediately beneath the probe (typically 1 mm(3) in tissues), whereas FDPM typically samples larger regions of tissues. Optical-property values for human skull, white matter, scar tissue, optic nerve, and tumors are reported that show distinct absorption and scattering differences between structures and a dependence on the phase-function parameter gamma.

Surgical crown lengthening of the maxillary anterior dentition: aesthetic considerations

Recent patient interest in aesthetic treatment has resulted in the development of advanced surgical and restorative procedures that are capable of conservatively addressing such objectives. While numerous materials and techniques have been developed accordingly, each must respect specific biological criteria in order to be successful. This article demonstrates the implementation of surgical periodontal plastic and restorative procedures that facilitate the full-mouth rehabilitation of a patient who presented with excessive wear of the natural dentition. The procedure described is specific for the maxillary anterior.

Digital holography for quantitative phase-contrast imaging

We present a new application of digital holography for phase-contrast imaging and optical metrology. This holographic imaging technique uses a CCD camera for recording of a digital Fresnel off-axis hologram and a numerical method for hologram reconstruction. The method simultaneously provides an amplitude-contrast image and a quantitative phase-contrast image. An application to surface profilometry is presented and shows excellent agreement with contact-stylus probe measurements.

Role of tissue structure in photon migration through breast tissues

Photon migration has been investigated experimentally in vitro on human breast tissues, bovine liver, tissue phantoms, and theoretically by Monte Carlo simulations and diffusion theory. The spatial intensity profiles have been measured at the output surface of a sample illuminated by a collimated beam. Experimental results have then been compared with simulations that assume the sample to be homogeneous. Measurements on phantoms, i.e., fat emulsion and microspheres suspension, and on liver are in good agreement with theory. On the other hand, the width of the intensity profiles measured on breast tissues (adipose and fibrous) are systematically larger than those measured on phantoms or calculated by simulations. The structure of these samples, not considered in simulations and not present in phantoms, explains these differences.

3'-5' L-capped-antisense oligodeoxynucleotides targeted at the SV40 T-antigen gene: pharmacological and biological properties

This paper reports on some pharmacological and biological properties of 22-mer antisense oligodeoxynucleotides which contain an L-deoxyribonucleoside at each terminus. Compared with natural compounds, of which they retain the DNA hybridizing ability and the cell uptake mechanism, the L-22-mers exhibited an increased resistance to phosphodiesterase degradation, an apparent higher intracellular concentration and a longer intracellular half life. Antiviral activity was not prominent.

Simultaneous polymerase chain reaction detection and restriction typing for the diagnosis of human genital papillomavirus infection

A polymerase chain reaction method has been developed which allows the simultaneous detection of the majority of clinically relevant HPV types. Degenerate HPV-specific primers direct the one-step amplification of a DNA region spanning E1 and E7 genes. This enables an immediate distinction between the two groups of papillomaviruses, characterized by high or low oncogenic potential, simply from the size of amplified DNA. The PCR product can be subjected to a second round of amplification with internal primers, which are specific for 7 high-risk HPV types, HPV-16, -18, -31, -33, -35, -45 and -58. Precise identification of one-step or two-step amplified DNA is done by endonuclease digestion with one or two enzymes. The detection sensitivity, which has been assessed using cloned HPV genomes and HeLa and CaSki cell lines, varies from a few tens to a few hundreds of viral genome equivalents. The accuracy of the method has been confirmed by examining cervical scrapings of 44 patients.

Synthesis and biological evaluation of N6-cycloalkyl derivatives of 1-deazaadenine nucleosides: a new class of anti-human immunodeficiency virus agents

A series of 1-deazaadenine nucleosides with the N6 nitrogen unsubstituted or bearing methyl or cycloalkyl substituents, with or without a chloro group in the 2-position, and with the glycosylic moiety being ribose (1-16), 2'-deoxyribose (17-32), or 2', 3'-dideoxyribose (33-48) were designed and synthesized starting from 5,7-dichloro-3H-imidazo[4,5-b] pyridine (50). These compounds were evaluated for their in vitro activity against human immunodeficiency virus type-1 (HIV-1) and herpes simplex virus type-1 (HSV-1). In addition they were tested for their ability to inhibit adenosine deaminase (ADA) from calf intestine. While the parent compounds 1-deazaadenosine (9), 2'-deoxy-1-deazaadenosine (25), and 2',3'-dideoxy-1- deazaadenosine (41) and the corresponding 2-chloro derivatives were inactive, nucleosides bearing cycloalkyl substituents on N6 exhibited moderate to good anti-HIV-1 activity, compared to 2',3'-dideoxyadenosine, with the degree and pattern of improvement depending on the structure of the sugar moiety. In general, 2'-deoxy- and 2',3'-dideoxy derivatives were more potent compounds than the corresponding ribose nucleosides. Compounds bearing a 6-cycloheptyl or cyclooctylamine were the most active in every series. The presence of a chloro group in the 2-position improved both activity and therapeutic index in every series, the most active compound being 2'-deoxy-2-chloro-N6-cycloheptyl-1-deazaadenosine (23; ED50 = 0.2 microM). On the other hand, most of these derivatives were inactive as anti-HSV-1 agents, showing a high degree of virus selectivity. The 1-deazaadenine derivatives were not substrates of adenosine deaminase, and some of them proved to be good inhibitors of the enzyme. However, the ADA inhibitory activity does not account for the antiviral potency since increased lipophilicity and steric hindrance of substituents resulted in derivatives much less active than the parent compounds.

Construction of a herpes simplex virus/varicella-zoster virus (HSV/VZV) thymidine kinase recombinant with the pathogenic potential of HSV and a drug sensitivity profile resembling that of VZV

A recombinant of herpes simplex virus (HSV) was constructed in which the HSV thymidine kinase (TK) gene was deleted and the varicella-zoster virus (VZV) TK gene was introduced into the US5 region under the control of the human cytomegalovirus IE promoter. Infection with the recombinant (R18) led to the induction of TK although the kinetics of synthesis resembled those of a 'late' gene product. The recombinant was virulent in the zosteriform mouse model with the pattern of pathogenesis similar to that of wild-type HSV-1. The sensitivity of the recombinant to several nucleoside analogues was assessed and in most cases (BVaraU, ACV and GCV) it resembled VZV rather than HSV. The enhanced sensitivity of the recombinant to BVaraU compared with wild-type HSV resulted in a far greater response to treatment with BVaraU as assessed in the mouse model.

A point mutation in the thymidine kinase gene is responsible for acyclovir-resistance in herpes simplex virus type 2 sequential isolates

A number of HSV-2 isolates, sequentially recovered from ulcerative ano-genital lesions of an AIDS patient during a prolonged treatment with acyclovir (ACV), have been studied at the molecular level. All of them were highly resistant to ACV (ACV-r) and shown to be virtually deficient in thymidine kinase (TK) activity. The ACV-r phenotype was demonstrated to be due to the production of truncated TK polypeptide. Structural alteration of this gene, as shown in one isolate, was caused by a chain-terminating mutation that originated from a cytidine deletion at position 520 of the TK open reading frame. This mutation generated a TGA stop codon 27 nucleotides downstream. An additional isolate was also recovered following ACV discontinuation and after a cycle of treatment with foscarnet. This isolate had lost the ACV-r trait and was characterized by a wild type TK sequence and by the production of a functional enzyme. Data presented confirm that a prolonged treatment with acyclovir can easily select ACV-r HSV-2 isolates carrying a TK- phenotype caused by a frameshift mutation. Although recovered from lesions tributary of different myelomers, these isolates may belong to the same strain that has undergone multiple cycles of reactivation and has possibly mutated during its axonal route to the skin.

Screening of HBV-DNA in chronic HBsAg carriers

A series of 52 serum samples from chronic HBsAg carriers was tested for the presence of HBV-DNA by means of the Polymerase Chain Reaction (PCR) and Liquid Phase Hybridization (LPH). The samples were obtained from two groups of patients: group A included 34 chronic HBsAg carriers ("healthy" individuals) without hepatocytolysis or viral replication; group B included 18 chronic HBsAg carriers with signs of hepatocytolysis (ALT levels at least twice the normal value) and activated markers of viral replication. PCR was superior to LPH in group A, with 7/34 versus 5/34 positive samples being detected, respectively. No difference in sensitivity was found between the two techniques in group B, since 9/18 samples were positive both cases. The data stress the need to adopt PCR for the HBV-DNA screening of HBeAg-/HBsAg+-carriers.

Acyclovir resistance in herpes simplex virus type 1: biochemical and functional studies on the thymidine kinase of the highly resistant R100 strain

The biochemical and functional properties of the thymidine kinase (TK) of the herpes simplex virus type 1 mutant R100, that is highly resistant to 9-(2-hydroxyethoxymethyl)guanine (acyclovir), are reported in comparison with the properties of its parental strain, wt. The mutant induced the production of a TK activity that accounted for only 10% of the wt one. This feature was not apparently related to a defective expression of the TK gene but it was rather connected to some functional characteristics of R100 enzyme. Although affinities of this enzyme for ATP and thymidine were unchanged, apparent Vmax values for thymidine were much reduced. In addition, affinities for antiviral analogues acyclovir, 9-(1,3-dihydroxymethyl)guanine (DHPG), 5-(2-bromovinyl)2'-deoxyuridine (BVdU), and 5-iodo-2'deoxycytidine (IdCyd) were drastically diminished (between 50-fold and more than 100-fold). This mutation therefore seems to affect the active site of the enzyme which is involved in the catalytic conversion of thymidine and in the binding of the analogues. The above features of HSV-1 R100 seem quite distinct from those of previously described HSV-1 resistant mutants.

[Esophageal prostheses by the endoscopic route (technics and results)]

The Authors reviewed their experience with palliative intubation for esophageal cancer. They have treated with endoscopic endoprostheses 197 patients with malignant strictures of the esophagus and/or cardias. Results and complications ore reported.