Time-related Decrease in Diffusion Capacity in HIV-infected Patients with Impaired Immune Function

The purpose of this study was to investigate acute and time-related changes in lung function, i.e. forced expiratory volume in 1 second (FEV1), vital capacity (VC) and transfer factor (KCO) in HIV-infected patients with CD4 cell counts less than 400 x 10(6)/l. 66 males with no history of HIV-related pulmonary symptoms participated in a prospective lung function study for 9 months with 3-month intervals between examinations. 15/66 patients (23%) developed acute pulmonary symptoms, i.e. dyspnea (n = 12), cough (n = 13), fever greater than 38 degrees C (n = 13) and interstitial infiltrates on the X-ray (n = 9). Among the 51 asymptomatic patients, a significant time-related decrease in KCO (median decrease of 7%) was found, whereas no significant change in FEV1 or VC was observed during the study. Baseline KCO, i.e. KCO at entry, was found to be significantly higher in the asymptomatic patients (102% predicted (pred.) than in those patients who developed pneumonia (88% pred.). Development of pulmonary symptoms was both followed by a significant decrease in KCO (median decrease 17%), FEV1 and VC. We therefore conclude that HIV-infected patients with impaired immune function have in the absence of pulmonary symptoms a decrease in KCO. In case of pneumonia an acute decrease in both KCO, FEV1 and VC occurs.

Evaluation of corn grain with the genetically modified input trait DAS-59122-7 fed to growing-finishing pigs

A growth performance experiment was conducted to assess the feeding value of a double-stacked transgenic corn grain for growing-finishing pigs. The genetically modified corn grain contained event DAS-59122-7, which expresses the Cry34/35Ab1 binary insecticidal protein for the control of corn rootworm. This modified transgenic grain is resistant to western corn rootworm and is also tolerant to herbicides containing the active ingredient glufosinate-ammonium. The modified grain (59122), a nontransgenic near-isoline grain (control corn), and a commercial corn (Pioneer brand hybrid 35P12) were grown in a 2005 production trial in individually isolated plots that were located 201 m apart. A total of 108 pigs were allotted to corn-soybean meal diets containing 1 of the 3 grains as the sole source of corn. There were 3 pigs per pen and 12 replicate pens per treatment. Pigs were fed grower diets from 37 to 60 kg, early finisher diets from 60 to 90 kg, and late finisher diets from 90 to 127 kg. Within each phase, data for ADG, ADFI, and G:F were calculated. At the conclusion of the experiment, pigs were slaughtered and data for carcass quality were collected. Differences between 59122 and the control corn were evaluated, with statistical significance at P<0.05. No differences in ADG, ADFI, or G:F between pigs fed the control corn and pigs fed the modified corn were observed during the grower, early finisher, or late finisher phases. For the entire experimental period, no difference between pigs fed the control and the 59122 corn were observed for final BW (128.9 vs. 127.1 kg), ADG (1.02 vs. 1.00 kg), ADFI (2.88 vs. 2.80 kg), or G:F (0.356 vs. 0.345 kg/kg). Likewise, no differences in dressing percentage (76.48 vs. 76.30%), LM area (49.8 vs. 50.4 cm(2)), 10th-rib back fat (2.20 vs. 2.12 cm), and carcass lean content (52.9 vs. 53.4%) were observed between pigs fed the control and the 59122 corn grain. It was concluded that the nutritional value of the modified transgenic corn grain containing event DAS-59122-7 was similar to that of the nontransgenic near-isoline control.

AIRE variations in Addison's disease and autoimmune polyendocrine syndromes (APS): partial gene deletions contribute to APS I

Autoimmune Addison's disease (AAD) is often associated with other components in autoimmune polyendocrine syndromes (APS). Whereas APS I is caused by mutations in the AIRE gene, the susceptibility genes for AAD and APS II are unclear. In the present study, we investigated whether polymorphisms or copy number variations in the AIRE gene were associated with AAD and APS II. First, nine SNPs in the AIRE gene were analyzed in 311 patients with AAD and APS II and 521 healthy controls, identifying no associated risk. Second, in a subgroup of 25 of these patients, AIRE sequencing revealed three novel polymorphisms. Finally, the AIRE copy number was determined by duplex quantitative PCR in 14 patients with APS I, 161 patients with AAD and APS II and in 39 healthy subjects. In two Scandinavian APS I patients previously reported to be homozygous for common AIRE mutations, we identified large deletions of the AIRE gene covering at least exon 2 to exon 8. We conclude that polymorphisms in the AIRE gene are not associated with AAD and APS II. We further suggest that DNA analysis of the parents of patients found to be homozygous for mutations in AIRE, always should be performed.

New immunological serum markers in bacteraemia: anti-inflammatory soluble CD163, but not proinflammatory high mobility group-box 1 protein, is related to prognosis

High mobility group-box 1 protein (HMGB1) is a late-onset proinflammatory cytokine. Soluble haemoglobin scavenger receptor (sCD163) is a specific marker of anti-inflammatory macrophages. The study purpose was to relate the levels of these new markers in bactaeremic patients to levels of well-known pro- and anti-inflammatory markers [procalcitonin, lipopolysaccharide (LPS)-binding protein, interleukin (IL)-6, IL-10] and to evaluate the levels in relation to disease severity and aetiology. A total of 110 patients with bacteraemia were included in a prospective manner from the medical department at a large Danish university hospital. Levels of HMGB1 and sCD163 were higher in patients with bacteraemia compared to controls (P < 0.001). HMGB1 correlated with proinflammatory molecules [procalcitonin (PCT)] and traditional infectious parameters [C-reactive proteins (CRP), white blood cells (WBC) and neutrophils], whereas sCD163 correlated with levels of IL-6, IL-10 but not to lipopolysaccharide-binding protein (LBP), PCT or CRP. Levels of sCD163 and IL-6 were significantly higher among non-survivors compared to survivors (P < 0.05). Neither HMGB1 nor any of the proinflammatory markers were elevated in fatal cases compared to survivors. There was no statistically significant difference in HMGB1 and sCD163 levels in Gram-negative versus Gram-positive bacteraemia. HMGB1 reflects proinflammatory processes, whereas sCD163 reflects anti-inflammatory processes as judged by correlations with traditional marker molecules. sCD163 and IL-6, but not HMGB1, were prognostic markers in this cohort pointing to an anti-inflammatory predominance in patients with fatal disease outcome.

Energy and nutrient digestibility in NutriDense corn and other cereal grains fed to growing pigs1,2,3

Two experiments were conducted to measure the energy and nutrient digestibilities in NutriDense corn and other cereal grains. An additional objective was to evaluate the effect of balancing diets with AA on the values measured for DE and ME of corn varieties. In Exp. 1, 6 growing pigs were fitted with a T-cannula in the distal ileum and allotted to a 6 x 6 Latin square design to measure apparent ileal digestibility (AID) and standardized ileal digestibility (SID) values for CP and AA in NutriDense corn, yellow dent corn, barley, wheat, and sorghum. Diets based on each of the 5 cereal grains were formulated, along with a N-free diet. Results of this experiment showed that the AID for most indispensable AA were greater (P < 0.05) in NutriDense corn and wheat than in the other cereal grains. The SID for Lys in NutriDense corn (77.6%) was greater (P < 0.05) than in yellow dent corn (68.5%), and sorghum (56.9%), but not different from wheat (75.1%) and barley (71.7%). The SID for Arg and Met in NutriDense corn also were greater (P < 0.05) than in yellow dent corn (88.1 and 87.2% vs. 84.5 and 82.8%, respectively). For the remaining indispensable AA, no differences in SID between NutriDense corn and yellow dent corn were observed. For all AA, the lowest values (P < 0.05) for AID and SID were obtained for sorghum. If calculated as grams of standardized ileal digestible AA per kilogram of DM, concentrations of all indispensable AA in NutriDense corn were greater (P < 0.05) than in yellow dent corn, but barley and wheat had greater concentrations of most AA than yellow dent corn and NutriDense corn. In Exp. 2, 12 growing barrows were placed in metabolism cages, and the DE and ME of NutriDense corn and yellow dent corn were measured. Both grains were used in diets without or with crystalline AA supplementation. Each diet was fed to 6 pigs in a 2-period, changeover design. The DE and the ME in NutriDense corn (4,004 and 3,922 kcal/kg of DM, respectively) were greater (P < 0.01) than in yellow dent corn (3,878 and 3,799 kcal/kg of DM, respectively). Values for DE and ME were not affected by the addition of crystalline AA to the diets. It is concluded that NutriDense corn has a greater value than yellow dent corn in diet formulations due to increased concentrations of digestible, indispensable AA and energy. However, barley and wheat have greater concentrations, whereas sorghum has lower concentrations, of many digestible AA than NutriDense corn.

Mortality after discharge from the intensive care unit during the early weekend period: a population-based cohort study in Denmark

BACKGROUND

As a result of a shortage of intensive care capacity, patients may be discharged prematurely early during weekends which may lead to an increased mortality and risk of readmission to intensive care units (ICU). We examined whether discharge from the ICU during the first part of the weekend was associated with an increased mortality and readmission to the ICU.

METHODS

The study was conducted at a university clinic of internal medicine and included all patients admitted for the first time to the ICU, and discharged alive in the period 1 January 2001 to 31 December 2005. Patients were divided in those discharged between 00.00 h Friday and 24.00 h Saturday (weekend group) and those discharged Sunday to Thursday (non-weekend group). The main outcome was time from discharge from the ICU to the combined endpoint death or re-admission to ICU which ever came first. We used Kaplan-Meier analysis and Cox's proportional-hazards regression to compute survival curves and risk ratio estimates.

RESULTS

There were 228 patients in the weekend group and 555 patients in the non-weekend group. Crude and adjusted 28-day risk ratio of the combined endpoint was 1.50 [95% confidence interval (CI): 1.15-1.97] and 1.43 (1.09-1.87) in the weekend group. Although an increased risk of death was observed in the weekend group immediately after discharge from the ICU, the difference in mortality between the two groups had disappeared after 2 years.

CONCLUSION

Medical patients discharged from the ICU early in the weekends seem to have an increased mortality and risk of readmission to the ICU.

Genotypic Drug Resistance and Long-Term Mortality in Patients with Triple-Class Antiretroviral Drug Failure

Objective

To examine the prevalence of drug-resistance-associated mutations in HIV patients with triple-drug class virological failure (TCF) and their association with long-term mortality.

Design

Population-based study from the Danish HIV Cohort Study (DHCS).

Methods

We included all patients in the DHCS who experienced TCF between January 1995 and November 2004, and we performed genotypic resistance tests for International AIDS Society (IAS)-USA primary mutations on virus from plasma samples taken around the date of TCF. We computed time to all-cause death from date of TCF. The relative risk of death according to the number of mutations and individual mutations was estimated by Cox regression analysis and adjusted for potential confounders.

Results

Resistance tests were done for 133 of the 179 patients who experienced TCF. The median number of resistance mutations was eight (interquartile range 2–10), and 81 (61%) patients had mutations conferring resistance towards all three major drug classes. In a regression model adjusted for CD4+ T-cell count, HIV RNA, year of TCF, age, gender and previous inferior antiretroviral therapy, harbouring ≥9 versus ≤8 mutations was associated with increased mortality (mortality rate ratio [MRR] 2.3 [95% confidence interval (CI) 1.1–4.8]), as were the individual mutations T215Y (MRR 3.4 [95% CI 1.6–7.0]), G190A/S (MRR 3.2 [95% CI 1.6–6.6]) and V82F/A/T/S (MRR 2.5 [95% CI 1.2–5.3]).

Conclusions

In HIV patients with TCF, the total number of genotypic resistance mutations and specific single mutations predicted mortality.

Digestibility of energy and phosphorus in ten samples of distillers dried grains with solubles fed to growing pigs1

An experiment was conducted to measure DE and ME and the apparent total tract digestibility (ATTD) of energy, N, and P in distillers dried grains with solubles (DDGS) fed to growing pigs. Ten sources of DDGS were obtained from ethanol plants in South Dakota and Minnesota, and 11 diets were formulated. One diet was based on corn (96.8%), limestone, salt, vitamins, and microminerals. Ten additional diets were formulated by mixing the corn diet and each of the 10 sources of DDGS in a 1:1 ratio. Eleven growing pigs (initial BW of 29.3 +/- 0.42 kg) were allotted to an 11 x 11 Latin square design, with 11 periods and 11 pigs. Each of the 11 diets was fed to each pig during 1 period. Pigs were placed in metabolism cages that allowed for the total, but separate, collection of feces and urine. Samples were analyzed for GE, N, and P and energy and N balances, and the ATTD of GE, N, and P were calculated for each diet. By subtracting the contribution from the corn diet to the DDGS-containing diets, the energy and N balances and the ATTD for GE, N, and P for each source of DDGS were calculated. Results of the experiment showed that the DE and ME differed (P < 0.001) among the 10 sources of DDGS (3,947 to 4,593 kcal of DE/kg of DM and 3,674 to 4,336 kcal of ME/kg of DM). The average DE and ME in DDGS were 4,140 and 3,897 kcal/kg of DM, respectively. These values were not different from the DE and ME in corn (4,088 and 3,989 kcal/kg of DM, respectively). Based on the analyzed GE and nutrient composition of DDGS and the calculated values for DE and ME, prediction equations for DE and ME were developed. These equations showed that DE and ME in DDGS may be predicted from the concentration of ash, ether extract, ADF, and GE. The retention of N from DDGS was greater (P < 0.001) than from corn, but when calculated on a percentage basis, the N retention did not differ between DDGS and corn. The ATTD of P in DDGS was 59.1% on average for the 10 samples. This value was greater (P < 0.001) than the ATTD of P in corn (19.3%). It is concluded that the DE and ME in DDGS is not different from the DE and ME in corn. However, if DDGS is included in diets fed to growing swine, a greater portion of the organic P will be digested and absorbed, thus reducing the need for adding inorganic P to the diets.

Apparent and true total tract digestibility of phosphorus in field peas (Pisum sativum L.) by growing pigs

The apparent (ATTD) and true (TTTD) total tract digestibility of P in field peas were measured using growing pigs. Two diets based on field peas without or with microbial phytase were formulated. A P-free diet was also formulated to measure endogenous losses of P. Results of the experiment showed that the ATTD and TTTD of P in field peas with microbial phytase (65.9 and 72.3%, respectively) were greater (P < 0.01) than in field peas without microbial phytase (55.0 and 60.8%, respectively). The addition of microbial phytase to field peas also reduced (P < 0.01) the excretion of P in the feces (from 5.77 to 4.09 g/5 d). Key words: Digestibility, endogenous losses, field peas, phosphorus, pig

The influence of dietary field peas (Pisum sativum L.) on pig performance, carcass quality, and the palatability of pork

An experiment was conducted to test the hypothesis that field peas may replace soybean meal in diets fed to growing and finishing pigs without negatively influencing pig performance, carcass quality, or pork palatability. Forty-eight pigs (initial average BW 22.7 +/- 1.21 kg) were allotted to 1 of 3 treatments with 2 pigs per pen. There were 8 replications per treatment, 4 with barrows and 4 with gilts. The treatments were control, medium field peas, and maximum field peas. Pigs were fed grower diets for 35 d, early finisher diets for 35 d, and late finisher diets for 45 d. Pigs receiving the control treatment were fed corn-soybean meal diets. All diets fed to pigs receiving the medium field peas treatment contained 36% field peas and varying amounts of corn; soybean meal was also included in the grower and the early finisher diets fed to pigs on this treatment. In contrast, no soybean meal was included in diets fed to pigs on the maximum field peas treatment, and field peas were included at concentrations of 66, 48, and 36% in the grower, early finisher, and late finisher diets, respectively. Pig performance was monitored within each phase and for the entire experimental period. At the conclusion of the experiment, carcass composition, carcass quality, and the palatability of pork chops and pork patties were measured. Results showed that there were no effects of dietary treatments on ADFI, ADG, or G:F. Likewise, there were no differences in carcass composition among the treatment groups, but gilts had larger (P = 0.001) and deeper (P = 0.003) LM, less backfat (P = 0.007), and a greater (P = 0.002) lean meat percentage than barrows. The pH and marbling of the LM, and the 10th rib backfat were not influenced by treatment, but there was a trend (P = 0.10) for more marbling in barrows than in gilts. The subjective color scores (P = 0.003) and the objective color score (P = 0.06) indicated that dietary field peas made the LM darker and more desirable. Pork chops from pigs fed field peas also had less (P = 0.02) moisture loss compared with chops from pigs fed the control diet. Treatment or sex did not influence palatability of pork chops or pork patties. In conclusion, field peas may replace all of the soybean meal in diets fed to growing and finishing pigs without negatively influencing pig performance, carcass composition, carcass quality, or pork palatability.

Intestinal morphology and enzymatic activity in newly weaned pigs fed contrasting fiber concentrations and fiber properties

The main objective of this study was to determine the effect of fiber source and concentration on morphological characteristics, mucin staining pattern, and mucosal enzyme activities in the gastrointestinal tract of pigs. The experiment included 50 pigs from 10 litters weaned at 4 wk of age (BW 8.6 +/- 1.4 kg) and divided into 5 treatment groups. Diets containing fiber of various physico-chemical properties and concentrations were formulated to contain 73, 104, or 145 g of dietary fiber/kg of DM. The diets were based on raw wheat and barley flours. Pectin and barley hulls, representing soluble and insoluble fiber sources, respectively, were used to increase the fiber concentration. The pigs were fed the experimental diets for 9 d, and then the pigs were euthanized and the entire gastrointestinal tract was removed. Tissue samples were taken from the mid and distal small intestine and from the mid colon. Inclusion of pectin in the diets significantly decreased (P < 0.001) ADFI and ADG compared with pigs fed no pectin. The villi and the crypts were shorter in pigs fed pectin-containing diets, but the villous height/crypt depth ratio was unaltered. Pectin significantly decreased the area of mucins in the crypts of the small intestine, indicating that the pigs fed the pectin-containing diet would probably be more susceptible to pathogenic bacteria, although this cannot be separated from the impact on ADFI. The lectin-binding pattern of the intestinal mucosa was unaffected by diet. The activity of lactase and maltase was increased in pigs fed diets with high fiber content, whereas sucrase activity was increased in pigs fed the pectin-containing diets. The activity of the peptidases, aminopeptidase N and dipeptidylpeptidase IV, was increased when feeding high fiber diets, whereas the activity of gamma-glutamyl transpeptidase remained unaffected by the experimental diets. In conclusion, the reduced feed intake observed with the pectin-containing diets could explain the lower villous height and crypt depth observed in this study. However, direct effects of pectin also are possible, and thus further study is warranted. Feeding pigs high insoluble fiber diets improved gut morphology by increasing villi length and increased mucosal enzyme activity when compared with pigs fed pectin-containing diets. The mucin content as determined by staining characteristics suggests that pigs fed high insoluble fiber diets might be better protected against pathogenic bacteria than pigs fed diets high in soluble fiber.

Amino acid and energy digestibility in ten samples of distillers dried grain with solubles fed to growing pigs1,2

The objective of this experiment was to measure the digestibilities of energy, CP, and AA in 10 samples of corn distillers dried grain with solubles (DDGS) and in corn fed to growing pigs. Twelve growing barrows (initial BW: 34.0 +/- 1.41 kg) were allotted to an 8 x 12 Youden square design with 8 periods and 12 animals. Ten of 12 diets were based on the 10 DDGS samples (66.7%), 1 diet was based on corn (97%), and the last diet was a N-free diet based on cornstarch and sucrose. Chromic oxide (0.3%) was included in all diets as an inert marker. Pigs were provided their respective diets at a level of 3 times their estimated energy requirement for maintenance. The apparent (AID) and standardized (SID) ileal digestibilities for CP and AA were measured in the 10 samples of DDGS and in corn using the direct procedure, but the apparent total tract digestibilities for DM and GE were estimated using the difference procedure. The concentration of DE in each sample of DDGS and in corn was also calculated. The results of the experiment indicated variation among the different sources of DDGS in AID and SID for Lys, which ranged from 35.0 to 55.9% and 43.9 to 63.0%, respectively. For Met, the SID varied between 73.9 and 84.7%. However, the variability among samples in the SID for CP, and for the indispensable AA other than Lys and Met, was relatively low and ranged between 6 and 8 percentage units (i.e., from 64.0 to 70.6%, 74.1 to 80.1%, and 67.4 to 75.3% for Thr, Trp, and Ile, respectively). The SID for Trp in corn (72.8%) was lower (P < 0.05) than in DDGS, but for the remaining indispensable AA, except Arg, the SID for corn were greater (P < 0.01) than for DDGS. The DE concentration in the 10 samples of DDGS varied (P < 0.001) from 3,382 to 3,811 kcal of DE per kg of DM. For corn, the DE was 3,845 kcal per kg of DM. It is concluded that the AID and SID for Lys vary among samples of DDGS, but for most other AA the AID and SID are relatively similar and vary only 6 to 8 percentage units among different samples. Future work should focus on identifying the reasons for the variation in the digestibility of Lys to avoid processing procedures that are detrimental to Lys digestibility.

Are Specific Antiretrovirals associated with an Increased Risk of Discontinuation due to Toxicities or Patient/Physician Choice in patients with Hepatitis C Virus Coinfection?

Background

Liver damage associated with hepatitis C (HCV) may influence the likelihood of experiencing discontinuation due to toxicities or patient/physician choice (TOXPC) in patients taking combination antiretroviral therapy (cART). Little information to address this concern is available from clinical trials as patients with HCV are often excluded.

Aims

To compare incidence rates of discontinuation due to TOXPC associated with specific antiretrovial drugs in patients with or without HCV.

Patients/methods

A total of 4929 patients from EuroSIDA under follow-up from January 1999 on a specific nucleoside pair (zidovudine/lamivudine, didanosine/stavudine, stavudine/lamivudine, or other) with a third drug (abacavir, nelfinavir, indinavir, nevirapine, efavirenz, lopinavir/ ritonavir or other boosted-protease inhibitor (PI)-containing regimen) and with known HCV serostatus were studied for the incidence of discontinuation of any nucleoside pair or third drug due to TOXPC. Incidence rate ratios were derived from Poisson regression models.

Results

In total 1358 patients had HCV (27.5%). During 12 799 person-years of follow-up there were 2141 discontinuations due to TOXPC for nucleoside pairs and 2501 for third drugs. The incidence of discontinuation due to TOXPC was consistently higher in patients with HCV after stratification by nucleoside pair or third drug. After adjustment for CD4+ count, gender, exposure group, time on HAART, region and treatment regimen, there were few differences in the rate of discontinuation due to TOXPC in those with HCV compared with those without for any nucleoside pairs or third drugs. Similar results were seen when concentrating on discontinuation due to toxicities alone.

Conclusions

Although patients with HCV generally had higher rates of discontinuation due to TOXPC compared with patients without HCV, there was little evidence to suggest that this was associated with any specific nucleoside pair or third drug used as part of cART. Our results do not suggest that any specific component of cART is more poorly tolerated in patients with HCV or that the presence of HCV should influence the choice between antiretrovirals used as part of a cART regimen.

Additivity of values for apparent and standardized ileal digestibility of amino acids in mixed diets fed to growing pigs1

The objective of this experiment was to determine whether the digestibility of CP and AA in a mixed diet fed to growing pigs is better predicted when based on standardized ileal digestibility coefficients (SID) or apparent ileal digestibility coefficients (AID). Eight growing pigs (initial BW = 92.1 +/- 3.19 kg) were surgically equipped with a T-cannula in the distal ileum and arranged in an 8 x 8 Latin square design with eight diets and eight periods. Three of the diets contained corn, soybean meal (SBM), or canola meal (CM) as the sole source of CP and AA. Four mixed diets also were formulated using corn and soybean meal (CS); corn and canola meal (CCM); soybean meal and canola meal (SCM); or corn, soybean meal, and canola meal (CSCM). A N-free diet was used to measure the basal ileal endogenous losses (IAAend) of CP and AA. Pigs were fed each of the eight diets during one 7-d period, and ileal digesta were collected during two 10-h periods on d 6 and 7. The AID values were calculated for CP and AA in all diets, except the N-free diet. By correcting the AID for IAAend, the SID for CP and AA in each of the seven protein-containing diets were calculated. As expected, the AID for CP and the majority of AA were greater in SBM than in corn and CM (P < 0.05); however, the SID for CP and most AA did not differ between corn and SBM. For the majority of the AA, SID were less (P < 0.05) in CM than in the other two ingredients. Using the AID and the SID that were measured for CP and AA in corn, SBM, and CM, the AID and the SID in the four mixed diets were predicted and compared with the measured values for these diets. For the three mixed diets containing corn, the measured AID for CP and most AA were greater (P < 0.05) than the predicted AID, but with a few exceptions, no differences between predicted and measured values for SID were observed. For the diet based on SCM, there were no differences between predicted and measured values regardless of the procedure used, except for the AID of Ser. The results of this experiment demonstrate that the digestibility coefficients for a mixed diet containing low-protein feed ingredients, such as corn, are more accurately predicted using SID than AID.

Thymidine Analogue Mutation Profiles: Factors Associated with Acquiring Specific Profiles and their Impact on the Virological Response to Therapy

Background

Studies have suggested that HIV-1 may develop thymidine analogue mutations (TAMs) by one of two distinct pathways – the TAM1 pathway (including mutations 41L, 210W and 215Y) or the TAM2 pathway (including mutations 67N, 70R and 219E/Q) – under the pressure of a not fully suppressive thymidine-analogue-containing regimen.

Methods

Frozen plasma samples stored in the EuroSIDA repository were selected and sent to two central laboratories for genotypic analysis. We considered 733 patients with at least one genotypic test showing ≥1 TAMs (the first of these tests in chronological order was used). TAM1 and TAM2 genotypic profiles were defined in accordance with previous literature. Statistical modelling involved logistic regression and linear regression analysis for censored data.

Results

The observed frequencies of patterns classifiable as TAM1 or TAM2 profiles were markedly higher than the probabilities of falling into these classifications by chance alone. The chance of detecting a TAM2 profile increased by 25% per additional year of exposure to zidovudine. We found that mutations 67N and 184V were not associated with a particular TAM profile. In the presence of TAM2 profiles, the adjusted mean difference in the 6-month viral reduction was 0.96 log10 copies/ml (95% confidence interval: 0.20; 1.73) higher in patients who started stavudine-containing regimens instead of zidovudine-containing regimens.

Conclusions

This study provides evidence that the suggested TAM clustering is a real phenomenon and that it may be driven by which thymidine analogue the patients has used. In patients with TAM2-resistant viruses, stavudine appears to retain greater viral activity than zidovudine.

The long-term pharmacokinetics and safety of adding low-dose ritonavir to a nelfinavir 1250 mg twice-daily regimen in HIV-infected patients

OBJECTIVES

To evaluate the long-term pharmacokinetics and safety of adding ritonavir 100 mg twice-daily to a nelfinavir 1250 mg twice-daily regimen in HIV-infected patients.

METHODS

This was a prospective, randomized, open-label, controlled 24-week study. Sixteen patients receiving a nelfinavir 1250 mg twice-daily regimen with plasma viral load <1000 HIV-1 RNA copies/mL were randomized to continue treatment or to have ritonavir 100 mg twice-daily added. Safety, including fasting lipid levels, was evaluated at weeks 4, 12 and 24. Patients who were randomized to have ritonavir added (n=9) participated in three 12-h pharmacokinetic evaluations at baseline, week 4 and week 24.

RESULTS

Increases in median nelfinavir steady-state plasma concentrations at 12 h (C(12)) from 512 to 773 ng/mL [median difference 450 ng/mL; 95% confidence interval (CI) 116--1510 ng/mL] and in median active nelfinavir metabolite M 8 C(12) from 107 to 603 ng/mL (median difference 545 ng/mL; 95% CI 370--891) were seen after the addition of low-dose ritonavir (baseline to week 24). There were no differences between the nelfinavir or M 8 pharmacokinetic parameters at weeks 4 and 24. No significant changes or differences in the concentration of fasting total cholesterol, low-density lipoprotein (LDL) cholesterol or total triglycerides or in the occurrence of adverse events were observed within or between the two groups.

CONCLUSIONS

Nelfinavir and especially M 8 concentrations are increased when low-dose ritonavir is added to a nelfinavir-containing regimen. The combination seems to be safe and the nelfinavir/ritonavir regimen could be an option in patients with low nelfinavir+M 8 concentrations.

A Randomized Trial to Evaluate Lopinavir/Ritonavir versus Saquinavir/Ritonavir in HIV-1-Infected Patients: The Maxcmin2 Trial

Objective

To assess the rate of protocol-defined treatment failure and safety of lopinavir/ritonavir (LPV/r) and saquinavir/ritonavir (SAQ/r).

Design

Open-label, prospective, randomized (1:1), international multi-centre trial.

Methods

Adult HIV-1-infected patients were assigned LPV/r 400/100 mg twice daily or SAQ/r 1000/100 mg twice daily with two or more nucleoside reverse transcriptase inhibitors (NRTIs)/non-NRTIs. All patients, whether on or off the assigned treatment, were followed for 48 weeks.

Results

Of 339 randomized patients, 324 initiated assigned treatment (intention-to-treat/exposed [ITT/e] population). At 48 weeks, treatment failure occurred in 29/163 (18%) and 53/161 (33%) of patients in the LPV/r and SAQ/r arms, respectively (ITT/e, P=0.002, log rank test). In an analysis that also considered those patients who discontinued treatment as having failed treatment (ITT/e/discontinuation=failure), 40/161 (25%) LPV/r-treated individuals versus 63/161 (39%) SAQ/R-treated individuals failed treatment ( P=0.005, log rank test). Discontinuation of the assigned treatment occurred in 23/163 (14%) patients in the LPV/r-treated group, compared with 48/161 (30%) in the SAQ/r-treated group (ITT/e; P=0.001). The primary reasons for premature discontinuation were non-fatal adverse events (LPV/r: 12/163; SAQ/r: 21/161) and patients’ choice (LPV/r: 7/163; SAQ/r: 8/161). In the on-treatment analysis of time to treatment failure, no difference was observed between the two arms ( P=0.27, log rank test).

Conclusion

LPV/r had better antiretroviral effects compared with SAQ/r at the doses and in the formulations studied. This may have been a result of patients’ preferences and ability to adhere to assigned therapy, rather than a result of differences in the intrinsic potency of the study protease inhibitors.

Resistance profiles and adherence at primary virological failure in three different highly active antiretroviral therapy regimens: analysis of failure rates in a randomized study

OBJECTIVES

To investigate the interplay between resistance and adherence in the virological failure of three fundamentally different highly active antiretroviral therapy (HAART) regimens.

METHODS

We retrospectively identified 56 verified primary virological failures (viral load >400 HIV-1 RNA copies/mL) among 293 patients randomized to two nucleoside reverse transcriptase inhibitors (NRTIs)+ritonavir+saquinavir (RS-arm) (n=115), two NRTIs+nevirapine+nelfinavir (NN-arm) (n=118), or abacavir+stavudine+didanosine (ASD-arm) (n=60) followed up for a median of 90 weeks. Data on adherence were collected from patient files, and genotyping was performed on plasma samples collected at time of failure.

RESULTS

Treatment interruption or poor adherence was mainly caused by side effects and accounted for 74% of failures, and was associated with absence of resistance mutations. In the 30 failing patients not switched from randomized treatment, we found resistance in two of 12 patients in the RS-arm (M184 V only), four of six patients in the NN-arm [all four had non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations], and seven of 12 patients in the ASD-arm (NRTI mutations only). Two adherent patients on randomized treatment failed in the RS-arm, none in the NN-arm, and six in the ASD-arm.

CONCLUSIONS

Primary virological failure was caused mainly by treatment interruption. No primary protease inhibitor (PI) mutations were found in patients failing on boosted saquinavir, whereas resistance to NNRTIs and NRTIs was prevalent in several patients failing on regimens based on these medications.

Baseline Resistance and Virological Outcome in Patients with Virological Failure who Start a Regimen Containing Abacavir: Eurosida Study

Objectives

To investigate the ability of several HIV-1 drug-resistance interpretation systems, as well as the number of pre-specified combinations of abacavir-related mutations, to predict virological response to abacavir-containing regimens in antiretroviral therapy-experienced, abacavir-naive patients starting an abacavir-containing regimen in the EuroSIDA cohort.

Patients and methods

A total of 100 HIV-infected patients with viral load (VL) >500 copies/ml who had a plasma sample available at the time of starting abacavir (baseline) were included. Resistance to abacavir was interpreted by using eight different commonly used systems that consisted of rules-based algorithms or tables of mutations. Correlation between baseline abacavir-resistance mutations and month 6 virological response was performed on this population using a multivariable linear regression model accounting for censored data.

Results

The baseline VL was 4.36 log10 RNA copies/ml [interquartile range (IQR): 3.65–4.99 log10 RNA copies/ml] and the median CD4 cell count was 210 cells/μl (IQR: 67–305 cells/μl). Our patients were pre-exposed to a median of seven antiretrovirals (2–12) before starting abacavir therapy. The median (range) number of abacavir mutations (according to the International AIDS Society-USA) detected at baseline was 3.5 (0–8). Overall, the Kaplan–Meier estimate of the median month 6 VL decline was 0.86 log10 RNA copies/ml [95% confidence intervals (95% CI): 0.45–1.24]. The VL in those patients ( n=31) who intensified treatment by adding only abacavir decreased by a median 0.20 log10 RNA copies/ml (95% CI: -0.18; +0.94). The proportion of patients who harboured viruses fully resistant to abacavir among the eight genotypic resistance interpretation algorithms ranged from 12% [Agence Nationale de Recherches sur le SIDA (ANRS)] to 79% [Stanford HIV RT and PR Sequence Database (HIVdb)]. Some interpretation systems showed statistically significant associations between the predicted resistance status and the virological response while others showed no consistent association. The number of active drugs in the regimen was associated with greater virological suppression (additional month 6 VL reduction per additional sensitive drug=0.51, 95% CI: 0.15–0.88, P=0.006); baseline VL was also weakly associated (additional month 6 VL reduction per log10 higher=0.30, 95% CI: -0.02; +0.62, P=0.06). In contrast, the number of drugs previously received was associated with diminished viral reduction (additional month 6 VL reduction per additional drug=-0.14, 95% CI: -0.28; 0.00, P=0.05).

Conclusions

Our results revealed a high degree of variability among several genotypic resistance interpretation algorithms currently in use for abacavir. Therefore, the interpretation of genotypic resistance for predicting response to regimens containing abacavir remains a major challenge.