The resilience of soil erosion rates under historical land use change in agroecosystems of Southern Spain.

Land use change (LUC) is identified as one of the main drivers of soil erosion in the Mediterranean. However, very little information exists regarding the relationship between land use and erosion over longer time periods and on regional scales. We quantified the LUC in Southern Spain between 1956 and 2018, examining its effect on soil erosion and assessing the mitigation role of the permanent grassland (PG). The land use influence on erosion is represented by the RUSLE's C-factor, which was modelled using the Monte Carlo Method (MCM) based on historical LUC. Moreover, future LUC scenarios by 2038 were developed by binary logistic model (scFS) and by a complete conversion of PG to cropland (scPC), permanent crop (scPP) and forest and natural (scFP). Historically, Southern Spain has experienced an impressive intensification of its agricultural system. While soil loss variation is noted within the classes, no big variation is observed in cumulative erosion on a regional scale. The underlying reasons for this resilience are multifold, but mainly attributed to the fact that a small fraction of the total surface (20%), dominates total erosion (67%). The C-factor decrease in this area displays a LUC towards forest and natural area, suggesting an agriculture abandonment. On the other hand, the agricultural intensification that has taken place in the remainder of the area, contributes much less to overall soil erosion. Future LUC scenarios illustrate the importance of PG for erosion mitigation. scFS scenario does not project major changes. However, scCP and scPP, show an abrupt increase in regional erosion by 13% and 14%, while scFP shows a negligible reduction of erosion close to 0%. This allows to quantify the erosion mitigation offered by maintaining the PG and should be taken into account for future agricultural policy.

Prospective comparative evaluation of quantitative-elastosonography (Q-elastography) and contrast-enhanced ultrasound for the evaluation of thyroid nodules: preliminary experience.

PURPOSE: To assess the effectiveness of semiquantitative elastosonography (Q-elastography) compared with contrast-enhanced ultrasound (CEUS) in differentiating the nature of thyroid nodules. METHODS AND MATERIALS: Forty-eight consecutive patients (35 males, 13 females, range: 34-69 years, mean: 49.4 years), candidate to surgery, previously detected at color-Doppler ultrasound (CDUS), were prospectively examined with elastosonography with dedicated semiquantitative software (Q-Elastography, Toshiba XG) and CEUS (Technos Mylab 70 Gold X, and Toshiba XG) before surgery. CEUS and elastosonography were evaluated by two investigators in consensus. Comparison between the CEUS pattern and elastonographic strain ratio observed and expected frequencies for the diagnoses was evaluated with χ(2) test or with Fisher exact test. RESULTS: Fifty-three nodules (19 papillary carcinoma, 32 hyperplasia, and 2 follicular adenoma) in 48 patients were available for analysis. Regarding echogenicity score, sensitivity, specificity, PPV and NPV of conventional US were 81%, 50%, 56%, 77%; according to Q-elastography, sensitivity, specificity, PPV and NPV were 95%, 88%, 97% and 91% respectively; whereas concerning CEUS, sensitivity specificity PPV and NPV were 79%, 91%, 83% and 89% respectively. Both CEUS and Q-elastography were more specific than US (p<0.01), with not statistical significant difference with regard to sensitivity. CONCLUSIONS: The results of the present study suggest that Q-elastography is a valuable tool in the characterization of thyroid nodules and it seems to be more sensitive than CEUS.

Increasing diagnostic accuracy for thyroid nodules by an integrated multivariate approach: a methodological study.

OBJECTIVES: Current guidelines for diagnostic management of thyroid nodules are based on a linear approach, using categorial classifications to cluster diagnostic findings and they still lead to unnecessary surgery. A diagnostic scoring system, based on clinical, cytological and ultrasound findings is described. MATERIALS AND METHODS: Two groups of patients (168 and 55 pts) were used to compute a multivariate model and the discriminating threshold by ROC curves. The performance of the derived scoring system was assessed by a simulation on a third group of 60 patients, who had undergone surgery according to current guidelines. RESULTS: The scoring system displayed a sensitivity of 100%, specificity 53.3%, positive and negative predictive values of 68.1% and 100%. According to the scoring system, 16 out of 60 operations would have been saved. CONCLUSIONS: A scoring system can take into account in a more accurate way the full informative content of the fine-grained description of diagnostic and clinical features.

Risk of malignancy from thyroid nodular disease as an element of clinical management of patients with Hashimoto's thyroiditis.

BACKGROUND: Many studies have investigated the association between chronic lymphocytic thyroiditis (CLT) and papillary thyroid carcinoma (PTC), but clinical management of this condition has never been addressed specifically, even in recent guidelines. Surprisingly the likelihood of a nodule as being cancerous in a CLT has never been explicitly expressed in terms of relative risk. METHODS: This study was based on a retrospective analysis of 404 patients undergoing total thyroidectomy. RESULTS: Sixty-nine patients (17.1%) had histological findings of true CLT, and 36.2% had concurrent PTC versus 22.6% of patients in the non-CLT group (p < 0.05), with a tumour risk in the CLT group of ×1.6 (95% CI = 1.21-1.94, likelihood ratio = +1.63). CONCLUSIONS: Patients with CLT and a nodular condition have a ×1.6 increased risk of harbouring a PTC. Moreover, these patients develop multicentric PTC more frequently, and, as a result, total thyroidectomy should always be considered.

Echocardiography and cardiac assist devices.

Mechanical circulatory support is, nowadays, a well established treatment modality for end stage heart failure. Patients candidate for cardiac transplantation who decompensate while awaiting graft can be supported by long-term left ventricular assist devices (long-term LVAD). These devices are intracorporeal pumps, expensive and complicated to install, but offer the advantages of a high cardiac output and a good patient mobility. Echocardiography is usually applied to any kind of LVAD to accomplish: preoperative evaluation to exclude contraindications, intraoperative when circulatory support starts to assess left ventricular (LV) filling and unloading, postoperative evaluation during intensive care unit course to prevent hypovolemia, cardiac tamponade and right ventricular failure, controls during assistance for suspected device malfunction. Short-term devices are utilized as acute support after the initial resuscitation of the patient. These devices are bedside extracorporeal pumps, less expensive and less complicated to install. They provide a brief but sufficient time to wait patient recovery (''bridge to recovery'') or to evaluate further therapies (''bridge to long-term device'' or ''bridge to transplantation''). Echocardiography has an important role during implantation to guide cannulae positioning, to prevent insufficient LV unloading, to detect echo contrast enhancement with blood stagnation and intracardiac clot formation, to titrate pharmacologic support, and to assess myocardial recovery.

Impella recover 100 microaxial left ventricular assist device: the Niguarda experience.

BACKGROUND: The Impella Recover 100 (IR100) is an intravascular microaxial blood pump used to support blood circulation for a maximum of 7 days in cases of reduced left ventricular function, for example in postcardiotomy low output syndrome or in cardiogenic shock after acute myocardial infarction. MATERIALS AND METHODS: We supported five patients with the IR100. The mean age, cardiac index (CI), and ejection fraction (EF) of our population were 42 years, 1.83 L/min/m(2), and 20%, respectively. Two patients (group A) with ischemic dilated cardiomyopathy were bridged to heart transplant. Two patients (group B) with fulminan myocarditis and septic shock were bridged to recovery. One patient, with severe valvular cardiomyopathy who underwent aortic valve replacement and mitral valve annuloplasty, was supported to weaning from ECC. RESULTS: Mean support time was 9.8 +/- 2.3 days. Only one acute myocarditis patient died from a severe vasoplegic syndrome despite maximal inotropic and vasoactive support. Both group A patients were successfully transplanted. Among group B, the second patient resolved the septic status and was slowly weaned from the device and discharged home with moderate improvement of LV function (EF = 40%). Patient C was weaned from the IR100 and electively placed on the heart transplant recipient list. CONCLUSIONS: IR100 is a device that in our experience can be utilized for various indications for short-term support. In compromised patients where a traditional LVAD is contraindicated, the IR100 showed good results, for it is minimally invasive and does not need ECC or systemic anticoagulation.

Risk management of HBsAg or anti-HCV positive healthcare workers in hospital.

Recommendations are made for controlling the transmission of the hepatitis B and hepatitis C viruses from healthcare workers to patients. These recommendations were based both on the literature and on experts' opinions, obtained during a Consensus Conference. The quality of the published information and of the experts' opinions was classified into 6 levels, based on the source of the information. The recommendations can be summarised as follows: all healthcare workers must undergo hepatitis B virus vaccination and adopt the standard measures for infection control in hospitals; healthcare workers who directly perform invasive procedures must undergo serological testing and the evaluation of markers of viral infection. Those found to be positive for: 1) HBsAg and HBeAg, 2) HBsAg and hepatitis B virus DNA, or 3) anti-hepatitis C virus and hepatitis C virus RNA must abstain from directly performing invasive procedures; no other limitations in their activities are necessary. Infected healthcare workers are urged to inform their patients of their infectious status, although this is left to the discretion of the healthcare worker; whose privacy is guaranteed by law. If exposure to hepatitis B virus occurs, the healthcare worker must undergo prophylaxis with specific immunoglobulins, in addition to vaccination.

A randomized trial comparing the introduction of ritonavir or indinavir in 1251 nucleoside-experienced patients with advanced HIV infection.

ISS-IP1, a multicenter, randomized, 48-week open trial, was designed to compare the introduction of ritonavir or indinavir in patients with previous nucleoside experience and CD4+ cell counts below 50/mm3. Concomitant antiretroviral treatment with nucleoside analogs was allowed. Primary efficacy measures were survival and time to a new AIDS-defining event or death, analyzed through the whole period of observation by the intention-to-treat approach. Primary toxicity measures were time to treatment discontinuation and adverse events, grade at least 3/serious, analyzed by an on-treatment approach. Evaluation-of efficacy also included CD4+ cell and RNA response. The trial enrolled 1251 patients in 5 months. At baseline, mean CD4+ cell count was about 20 cells/mm3 and mean HIV RNA copy number was 4.9 log10/ml in both groups. Overall, 402 patients in the ritonavir group and 250 patients in the indinavir group permanently discontinued the assigned treatment (relative risk, 1.96; 95% CI, 1.68-2.30; p = 0.0001), with most of this difference dependent on a higher number of discontinuation for adverse events in the ritonavir group. After a mean follow-up of 307 days (ritonavir, 304; indinavir, 309), 124 deaths (ritonavir, 61; indinavir, 63; relative risk, 0.96; 95% CI, 0.67-1.36; p = 0.80) and 330 new AIDS-defining events (ritonavir, 170; indinavir, 160; relative risk, 1.05; 95% CI, 0.85-1.31; p = 0.60) were observed. CD4+ cell counts increased in both groups in patients still receiving treatment, with about 100 cells gained by week 24 and 150 cells gained by week 48. Body weight also increased over time in both groups. Analysis of RNA response showed a decrease of 1.5 log10 or higher in both treatment groups. Overall, 400 patients in the ritonavir group and 338 patients in the indinavir group developed at least one grade 3/serious new adverse event during follow-up (relative risk, 1.48; 95% CI, 1.28-1.72; p = 0.0001). Favorable CD4+ cell and RNA responses at 24 and 48 weeks were observed in both groups of patients remaining on treatment. Indinavir showed slightly better effects in sustaining RNA, CD4+ cell, and body weight responses. Ritonavir and indinavir results were comparable in terms of clinical outcome (survival and AIDS-defining events).

Effect of two different combinations of antiretrovirals (AZT+ddI and AZT+3TC) on cytokine production and apoptosis in asymptomatic HIV infection.

Nineteen HIV-seropositive antiretroviral therapy-naive and asymptomatic individuals (200-500 CD4/microl) were enrolled in a prospective study aimed at analyzing the immunologic and virologic effects of two different combinations of nucleoside reverse transcriptase inhibitors (AZT+ddI and AZT+3TC), and randomly assigned to one of the treatment group. Immunologic (CD4 and CD8 counts, mitogen-stimulated cytokine production, unstimulated and mitogen-stimulated apoptosis) and virologic (HIV viral load) determinations were performed pre-therapy and 15, 30, 90, 200 and 360 days after initiation of therapy. Results showed that the two combinations had comparable effects on increasing CD4 counts and the CD4/CD8 ratio and in reducing HIV viral load. In contrast, AZT+3TC was more efficient in improving interleukin-2 (IL-2) and interferon gamma (IFNgamma) production as well as the type 1/type 2 cytokine ratio and in down modulating the susceptibility of peripheral blood mononuclear cells to in vitro mitogen-stimulated apoptotic cell death. These data suggest that the combination of AZT+3TC has a stronger effect on potentially beneficial immune parameters (IL-2 production; reduction of apoptosis) than the one between AZT+ddI. The combination of AZT+3TC could be more advantageous in the therapy of HIV infection even when used in association with a protease inhibitor.

Acetylator phenotype prevalence in HIV-infected patients without previous trimethoprim-sulfamethoxazole hypersensitivity.

This trial was conducted to study the frequency of the slow acetylator phenotype in asymptomatic HIV patients having no previous reaction to sulfa-drugs, and to compare this frequency with the frequency found in healthy controls. Results show that HIV alone is not capable of modifying the acetylator phenotype; the prevalence of slow acetylator phenotype is the same in immune competent subjects and HIV-positive patients. It is more common in HIV-positive patients with a CD4+ lymphocyte count of less than 200 mm-3.

Intractable pruritus in HIV infection: immunologic characterization.

BACKGROUND: Severe, intractable pruritus, often associated with erythematopapular skin lesions and hypereosinophilia, is a condition observed in some nonatopic, HIV-infected patients. We performed immunovirologic analyses of this condition. METHODS: Immunologic (mitogen-stimulated production of cytokines, tumor necrosis factor-alpha [TNF-alpha], and soluble CD23; serum levels of soluble CD23, ICAM-1, TNF-alpha, IgG, IgE, and IgA) and virologic (HIV viral load) parameters were analyzed in six patients with therapy-resistant pruritus. Hypereosinophilia was present in all these patients. Results were compared to those of seven HIV-seropositive individuals similar to the first one in terms of CD4 counts and clinical staging, but without pruritus. RESULTS: Hypereosinophilia; hyper-IgE and hyper-IgA; augmented interleukin (IL)-4, IL-5, and sCD23; and reduced interferon-gamma production by mitogen-stimulated peripheral blood mononuclear cells (PBMC) were detected when patients with pruritus were compared to HIV controls. HIV viral load was also augmented in patients in whom pruritus was present. CONCLUSIONS: The results suggest that therapy-resistant, intractable pruritus accompanied by hypereosinophilia may be used to define a subset of HIV-seropositive individuals showing prototypic hyperactivation of humoral immunity, and in whom augmented HIV viral load is present.

Pentoxifylline improves cell-mediated immunity and reduces human immunodeficiency virus (HIV) plasma viremia in asymptomatic HIV-seropositive persons.

The effects of pentoxifylline on immunologic and virologic parameters were evaluated in 10 human immunodeficiency virus-infected patients not receiving antiretroviral treatment. Patients were asymptomatic, had 300-500 CD4 cells/microL, and received pentoxifylline (1200 mg/day orally) for 4 months. Peripheral blood mononuclear cells were tested before and at five time points during therapy. A transient increase in CD4 cells was observed in 8 of 9 patients, and CD8 cells increased in 7 of 9 patients. These increases were negatively correlated with susceptibility to in vitro mitogen-stimulated apoptotic cell death. Pentoxifylline had a temporary effect on mitogen-stimulated cytokine production; thus, interferon-gamma, interleukin (IL)-2, tumor necrosis factor-alpha, and lymphotoxin increased more than IL-10. Pentoxifylline also potentiated antigen-stimulated IL-2 production and proliferation in 8 of 9 patients and induced significant but transient decreases in plasma viremia in 7 of 9 patients. These preliminary findings suggest that pentoxifylline in vivo has an interesting but temporary influence on both immunologic and virologic parameters.

A randomized trial (ISS 902) of didanosine versus zidovudine in previously untreated patients with mildly symptomatic human immunodeficiency virus infection.

In this multicenter study (ISS 902), 554 previously untreated patients with <500 CD4 cells/mm3 and mildly symptomatic human immunodeficiency virus disease were randomized to receive zidovudine or didanosine (ddI). After a mean follow-up of 20 months, 80 patients (40 zidovudine, 40 ddI) had died and 146 had at least one AIDS-defining event (73 zidovudine, 73 ddI). Overall, no difference was found between treatments with respect to progression to AIDS or death. The analysis of relative risk (RR) of progression over time, however, showed an initially minor risk for zidovudine patients and an inversion in the zidovudine-ddI RR in the second and third years of follow-up. Didanosine showed a greater effect on CD4 cell count response. The two drugs confirmed the toxicity patterns already reported in other trials, with a low occurrence of pancreatitis (ddI 1.3%, zidovudine 0.4%). The overall results suggest that, in this population, zidovudine and ddI monotherapies have comparable long-term clinical efficacy and that more powerful regimens should be preferred.

Italian multicentre study of didanosine compassionate use in advanced HIV infection. Italian BMS-906 Study Group.

The aim of the present study, a multicentre trial of didanosine (ddI) compassionate use, was to identify factors associated with a better outcome in patients given ddI monotherapy. Enrolled were 1047 HIV-positive patients intolerant of and/or unresponsive to zidovudine (ZDV) therapy, with CD4+ cell counts of < 200/microliter or AIDS. Didanosine was given at a dose of 250 mg b.i.d. (patients > or = 60 kg) or 167 mg b.i.d. (patients < 60 kg). Clinical examinations and laboratory tests were performed every two months. Endpoints included death, the occurrence of a new AIDS-defining disease, or permanent discontinuation of ddI for a severe adverse event. At entry, the median CD41 cell count was 47/microliter and the median duration of prior ZDV treatment 19 months; 446 patients (43%) were classified as having AIDS. Severe toxicity occurred in 143 subjects (14%); the frequency of pancreatitis was very low (0.2%). The benefit in terms of CD4+ cell counts was greater for patients whose counts exceeded 100/microliter at entry and remained at this level until month 12 in those patients still receiving treatment. Death and/or new AIDS-defining events were observed in 374 cases (36%) over a median follow-up of eight months. AIDS dementia was observed in 11 patients (1%). Multivariate analysis of survival without disease progression showed that the factors associated with a worse outcome include the severity of immunodepression, a diagnosis of AIDS at entry, and a history of both intolerance of and clinical resistance to ZDV. Surprisingly, the patients who had received previous prolonged treatment with ZDV had a better outcome. In conclusion, severely immunodepressed patients previously administered long-term monotherapy may receive a short-term benefit from being switched to another antiretroviral drug.

Sublingual versus injective immunotherapy in grass pollen allergic patients: a double blind (double dummy) study.

BACKGROUND: Injective immunotherapy is a well-known and recognized treatment for allergic diseases, but its safety has been questioned during recent years. Alternative administration routes have been proposed and there is a growing interest and experience in sublingual therapy. The safety of alternative routes is nonetheless a real advantage, so long as it is not counterbalanced by a loss of clinical benefit. OBJECTIVE: We have compared the efficacy of the same biologically standardized grass pollen extract administered through the injective or the sublingual route, in a group of 20 patients followed for two pollen seasons. METHODS: Both therapies were administered for 12 months according to a double-blind (double-dummy) plan; at the end of the trial the cumulative dosage of the sublingual therapy was 2.4 times higher than that of the injective therapy. Data about skin reactivity, symptoms and drugs scores during the pollen season, as well as total specific IgG and specific IgG4, during and after the trial, were obtained. RESULTS: Our data show that sublingual and injective therapy are equally effective according to subjective clinical parameters, with a statistically highly significant reduction of symptoms and drugs (P = 0.002 for symptoms and drugs in SLIT-treated patients; P = 0.002 for symptoms and P = 0.0039 for drugs in patients given injections). On the other hand, objective parameters (total specific IgG, specific IgG4, skin reactivity) changed only in patients treated with active injective therapy, with P < 0.001, P < 0.001 and P = 0.021, respectively. CONCLUSIONS: The discrepancies observed could be interpreted as a consequence of different mechanisms of actin of the two therapies or to the lack of close relationships between the clinical and the objective parameters which were considered here.

Immunological activation markers in the serum of African and European HIV-seropositive and seronegative individuals.

OBJECTIVE: The concentration of type 1 and type 2 cytokines and fibroblast-associated apoptosis-1 soluble receptor (sAPO-1/Fas) was analysed in the sera of Ugandan and Italian HIV-1-seropositive and seronegative individuals. The data were compared to determine whether the immunological status of these groups was different. METHODS: Sixty-seven Ugandan and 30 Italian HIV-positive patients were analysed and stratified according to CD4 counts (group 1, > 500 x 10(6)/l; group 2, 200-500 x 10(6)/l; group 3, < 200 x 10(6)/l). Sera from 15 Ugandan and 11 Italian HIV-negative blood donors were also analysed. Serum concentration of type 1 cytokines [interleukin (IL)-2, IL-12, and interferon (IFN)-gamma] and type 2 cytokines (IL-4 and IL-10), and sAPO-1/Fas were measured by enzyme-linked immunosorbent assay. RESULTS: Serum levels of IL-2, IFN-gamma and IL-10 but not of IL-4 and IL-12, were elevated in HIV-positive group 1 and 2 Africans compared with HIV-positive Italian individuals. IL-4 was mildly augmented in HIV-positive group 3 African patients. Serum concentration of sAPO-1/Fas was reduced in HIV-positive Africans compared with HIV-positive Italian individuals. Finally, serum levels of IL-2 and IL-10 were increased and sAPO-1/Fas reduced when sera of HIV-negative African healthy controls were compared with their Italian counterparts. The ratio of type 1/type 2 cytokines was roughly 1.0 in HIV-negative African controls, and much greater than 1.0 in HIV-negative Italian controls. CONCLUSIONS: These preliminary findings indicate that immune activation is present in African HIV infection. Furthermore, these data raise the possibility that abnormal immune activation and increased susceptibility to antigen-induced cell death is present even in HIV-negative African controls.

A randomized trial (ISS 901) of switching to didanosine versus continued zidovudine after the diagnosis of AIDS.

Although the efficacy of switching from zidovudine (AZT) to didanosine (ddI) has already been evaluated in controlled studies, prior investigations were not specifically designed to evaluate this issue in patients with acquired immune deficiency syndrome (AIDS). This open, randomized, multicenter study (ISS 901) was designed to evaluate the clinical benefit in patients with AIDS of switching to ddI after 6-18 months of AZT and no major intolerance. Patients were randomized to continue AZT, maintaining the current dosage at randomization (n = 79), or to receive ddI (n = 80) at the dosage of 375 mg and 250 mg b.i.d. for body weight > 60 and < or = 60 kg, respectively. Primary efficacy measures were survival and time to new AIDS-defining events, analyzed by the intent-to-treat approach. The two groups were comparable for baseline characteristics, follow-up (15 months), and time spent on allocated treatment. At the end of the study, 104 patients (48 AZT, 56 ddI) had died and 90 had at least one new AIDS-defining event (44 AZT, 46 ddI). Kaplan-Meier estimates of survival and of time to first new AIDS-defining event showed no differences between the treatment groups. No differences were detected in other efficacy measurements (p24 antigenemia, CD4+ count, Karnofsky score, and body weight), occurrence of severe toxicities, and treatment modifications. Pancreatitis occurred only in ddI-treated patients (6%). In our population of patients with advanced disease, switching from AZT to ddI did not produce apparent benefits, suggesting that application of this strategy earlier in the course of human immunodeficiency virus disease should be considered.

The role of HIV type 1 phenotype and genotype in long-term responders to zidovudine therapy.

We performed a cross-sectional and partly retrospective virological evaluation of 31 long-term responders (LTRs) to zidovudine (ZDV) (persistent increase in the CD4+ cell counts without progression of HIV infection throughout a period of ZDV therapy > 3 years) and 17 well-matched controls who developed a marked immunological deterioration over a 24-month period of ZDV therapy. The biological phenotype of HIV-1 was assessed by testing the capacity of the isolates to replicate in the MT-2, HUT-78, C-8166, and U-937 T cell lines, and mutations at codons 215 and 41 of RT were checked in proviral DNA from uncultured PBMCs. Show/low non-syncytium-inducing (S/L-NSI) and rapid/high syncytium-inducing (R/H-SI) variants were detected in 25 (81%) and 2 (6%) LTRs, respectively. HIV-1 could not be isolated in the remaining four LTRs (13%). Conversely, 12 of 17 (71%) controls yielded R/H-SI variants. Conversion from the S/L-NSI to R/H to R/H-SI phenotype occurred in 5 controls but in none of the 18 LTRs tested. Mutant sequences in proviral DNA from control PBMCs were consistently detected (94%), while a wild-type sequence of the residues investigated was found in the majority of LTRs (77%). In our series, patients who received immunological and clinical benefits even after prolonged ZDV treatment had S/L-NSI viruses and a low risk to develop ZDV resistance. Conversely, subjects who demonstrated an immunological and clinical deterioration yielded R/H-SI variants or shifted from S/L-NSI to R/H-SI phenotypes and were at higher risk to develop mutations indicating ZDV resistance.