Intervesicle cross-linking with integrin alpha IIb beta 3 and cyclic-RGD-lipopeptide. A model of cell-adhesion processes

We report the synthesis of a new integrin alpha(IIb)beta(3)-specific cyclic hexapeptide that contains an Arg-Gly-Asp (RGD) sequence and is coupled to a dimyristoylthioglyceryl anchor. We demonstrate that this ligand is useful to study specific integrin binding to membrane surfaces. With the help of biotinylated analogues of the peptide, a spacer of optimal length between the peptide and lipid moieties was searched for by evaluating the binding strength with an enzyme-coupled immunosorbent assay (ELISA) and by surface plasmon resonance (SPR). It was found to be strongly dependent on the length of the spacer introduced between the biotin and peptide moieties of the ligands, which consisted either of epsilon-aminohexanoic acid (epsilonAhx) or of epsilonAhx with two additional glycine units. Best results were obtained with c[Arg-Gly-Asp-D-Phe-Lys(Biot-Ahx-Gly-Gly)-Gly-] with dissociation constants of K(D) = 0.158 microM from ELISA and K(D) = 1.1 microM from SPR measurements. The analogous lipopeptide, c[Arg-Gly-Asp-D-Phe-Lys([dimyristoyl-3-thioglyceryl-succinimido -propanoyl]Ahx-Gly-Gly)-Gly], was used as a membrane-anchored integrin ligand. It is shown by fluorescence microscopy and cryo electron microscopy that integrin reconstituted into phospholipid vesicles binds to vesicles decorated with the lipopeptide, forming regularly spaced bridges between the two kinds of vesicles. The novel integrin-specific ligand allows establishment of new model systems for systematic studies of the self-organization of integrin clusters and focal adhesion complexes.

31P-CP-MAS NMR studies on TPP+ bound to the ion-coupled multidrug transport protein EmrE

The binding of tetraphenylphosphonium (TPP+) to EmrE, a membrane-bound, 110 residue Escherichia coli multidrug transport protein, has been observed by 31P cross-polarisation-magic-angle spinning nuclear magnetic resonance spectroscopy (CP-MAS NMR). EmrE has been reconstituted into dimyristoyl phosphatidylcholine bilayers. CP-MAS could selectively distinguish binding of TPP+ to EmrE in the fluid membrane. A population of bound ligand appears shifted 4 ppm to lower frequency compared to free ligand in solution, which suggests a rather direct and specific type of interaction of the ligand with the protein. This is also supported by the observed restricted motion of the bound ligand. The observation of another weakly bound substrate population arises from ligand binding to negatively charged residues in the protein loop regions.

Surface coating with cyclic RGD peptides stimulates osteoblast adhesion and proliferation as well as bone formation

The physiological inertness of synthetic implant materials often results in insufficient implant integration and limited acceptance of implants in tissues. After implantation the implant surface is often separated from the surrounding healthy and regenerating tissue, for example by a fibrous capsule. To avoid this host-versus-graft reaction, a strong mechanical contact between tissue and implant must be ensured. An enhanced contact between graft and the surrounding tissue can be provided by coating the implant with cell-adhesive molecules. The highly active and alpha(v)beta(3)- and alpha(v)beta(5)-integrin-selective peptide c(-RGDfK-) (f=D-phenylalanine) was functionalized with various linker molecules containing an acrylamide end group by using the lysine side chain of c(-RGDfK-). The acrylamide group can be used to bind the peptide covalently to poly(methyl methacrylate) (PMMA) surfaces. The coated surfaces effectively bind to murine osteoblasts as well as human osteoblasts in vitro when a minimum distance of 3.5 nm between surface and the constrained RGD sequence is provided. In contrast to osteoblasts in cell suspension, surface-bound osteoblasts show no apoptosis but proliferate by a factor of 10 over a 22 d period. Coating of inert implant surfaces with highly active and alpha(v)-selective peptides affords a marked improvement in osteoblast binding over current technologies. In vivo studies show that peptide-coated PMMA pellets implanted into the patella groove of rabbits are integrated into the regenerating bone tissue faster and more strongly than uncoated pellets.

International round-robin experiment to test the International Organization for Standardization total-scattering draft standard

An international round-robin experiment has been conducted among laboratories in different countries to test the measurement and the data-analysis procedures in the International Organization for Standardization draft standard ISO/DIS 13696 for measuring total scattering from low-scatter laser optics. Ten laboratories measured total backscattering from high-reflectance mirrors, 50% beam splitters, and antireflection-coated windows. Results were sent to the Laser Zentrum Hannover, which acted as coordinator and analyzed all the backscattering data. The results showed that the procedure in the draft standard was useful for measuring and reporting backscattering for low-scatter optics. Problems encountered in the round-robin experiment included the accumulation of particles on the surfaces, particularly on the high-reflectance mirrors.

In vivo antagonism with zidovudine plus stavudine combination therapy

Human immunodeficiency virus (HIV)-infected subjects receiving zidovudine were randomized either to add stavudine (d4T) or didanosine (ddI) to their current regimen or to switch to ddI or d4T monotherapy. After 16 weeks of therapy, the mean reduction in HIV RNA from baseline was 0.14 log(10) copies/mL in patients receiving d4T or zidovudine plus d4T. In subjects receiving ddI or ddI plus zidovudine, reductions were 0.39 and 0.56 log(10), respectively. CD4 cell counts remained stable or showed modest increases in all arms except the zidovudine plus d4T arm. Patients receiving zidovudine plus d4T showed progressive declines in CD4 cell counts with a median of 22 cells/mm(3) below baseline by 16 weeks. Examination of intracellular levels of d4T-triphosphate in 6 subjects was consistent with previous in vitro studies demonstrating pharmacologic antagonism between zidovudine and d4T. Analysis of these data suggests that zidovudine and d4T should not be prescribed in combination and that ddI provides greater antiviral activity than d4T in zidovudine-treated patients.

Epitope mapping of monoclonal antibodies directed to PAI-1 using PAI-1/PAI-2 chimera and PAI-1-derived synthetic peptides

Plasminogen activator inhibitor type-1 is a key regulatory protein of the fibrinolytic system that is involved in a variety of physiological and pathophysiological processes. A panel of 14 monoclonal antibodies directed against plasminogen activator inhibitor type-1 was analyzed regarding epitope specificity on plasminogen activator inhibitor type-1. For this purpose, chimera consisting of plasminogen activator inhibitor type-1 and another plasminogen activator inhibitor, plasminogen activator inhibitor type-2, with different portions of the respective wild-type proteins, were generated and plasminogen activator inhibitor type-1-derived 20-mer and 10-mer linear peptides were synthesized. Nine of the 14 monoclonal antibodies recognized an epitope located in the region between amino acid 76-188 of plasminogen activator inhibitor type-1, which encompasses the binding sites for vitronectin, heparin, and part of the fibrin binding region. Of these nine monoclonal antibodies, six reacted with a quadruple plasminogen activator inhibitor type-1 mutant (N152H, K156T, Q321L, M356I), and seven detected a plasminogen activator inhibitor type-1 deletion mutant (DeltaF111-H114). Two of the remaining five monoclonal antibodies recognized epitopes located between amino acid 209-227 and amino acid 352-371, respectively, while the other three antibodies reacted with wild-type plasminogen activator inhibitor type-1, only. Additional experiments revealed that two of the 14 mAbs neutralized and one monoclonal antibodies increased plasminogen activator inhibitor type-1 activity toward urokinase-type plasminogen activator, one of its target proteases.

Effect of zidovudine resistance mutations on virologic response to treatment with zidovudine-lamivudine-ritonavir: genotypic analysis of human immunodeficiency virus type 1 isolates from AIDS clinical trials group protocol 315.ACTG Protocol 315 Team

The effect of baseline drug resistance mutations on response to zidovudine, lamivudine, and ritonavir was evaluated in zidovudine-experienced persons infected with human immunodeficiency virus type 1 (HIV-1). Presence of the K70R mutation was associated with significantly higher plasma HIV-1 RNA levels at baseline. However, presence of resistance mutations did not affect the increase in plasma HIV-1 RNA during a 5-week drug washout, nor was there any effect on first-phase virus decay rates after initiation of therapy or on the probability of having plasma HIV-1 RNA levels <100 copies/mL at week 48. Polymorphisms at protease codons 10, 36, and 71 were associated with significantly faster second-phase decay rates. Suppression of plasma HIV-1 RNA despite presence of zidovudine resistance mutations implies that the presence of these mutations does not preclude a durable response to treatment with a potent 3-drug regimen.

Response to immunization with recall and neoantigens after prolonged administration of an HIV-1 protease inhibitor-containing regimen. ACTG 375 team. AIDS Clinical Trials Group

OBJECTIVES

To ascertain if immunization results in the restoration of responses to recall antigens, in the development of responses to presumed neoantigens, and to identify the virologic and immunologic correlates of these responses in persons with HIV-1 infection.

DESIGN AND SETTING

Open-label study carried out at three university-affiliated AIDS Clinical Trials Units in the United States.

SUBJECTS AND METHODS

Thirty-one subjects participating in AIDS Clinical Trials Group Protocol 375 who had received zidovudine, lamivudine, and ritonavir for at least 48 weeks. Subjects were immunized with tetanus toxoid (TT) at entry and with inactivated hepatitis A vaccine (hep A) and keyhole limpet hemocyanin (KLH) at entry and 6 weeks. The development of antibody, lymphocyte proliferative assay (LPA), and delayed-type hypersensitivity (DTH) responses after immunization were monitored.

RESULTS

The LPA and DTH responses to TT improved in 57 and 68% of participants, respectively; 73 and 65% developed enhanced LPA and DTH responses to KLH. Forty-eight percent of patients developed a four-fold increase in antibody concentration to tetanus. Seventy-three percent of patients without detectable hepatitis A antibodies at baseline developed antibodies after immunization. Eighty-three percent of patients experienced at least a four-fold rise in KLH antibody concentration. Immune activation and viral load predicted poor recall responses and the number of memory CD4+ T-cells predicted good responses to recall antigens. Naïve CD4+ T-cell numbers, decrease in viral load, increases in CD4+ and CD28+ cells, and decreases in immune activation were associated with responses to presumed neoantigens.

CONCLUSIONS

Most HIV-infected patients treated with potent combination antiretrovirals develop responses to recall and presumed neoantigens after immunization. Functional immune restoration in response to immunization is related to control of viral replication, decreased immune activation as well as to both quantitative and qualitative restoration of circulating T- lymphocyte subpopulations.

Immune reconstitution in the first year of potent antiretroviral therapy and its relationship to virologic response

The effects of 1 year of zidovudine, lamivudine, and ritonavir treatment on immune reconstitution were evaluated in 34 human immunodeficiency virus (HIV)-infected individuals. After 48 weeks of therapy, 20 (59%) subjects had <100 copies HIV RNA/mL. CD4+ T cells increased from a median of 192/mm3 at baseline to 362/mm3 at week 48. Lymphocyte proliferative responses to Candida normalized within 12 weeks, but responses to HIV and tetanus remained depressed throughout therapy. Alloantigen responses increased within 12 weeks and then declined to baseline levels. Recovery of delayed-type hypersensitivity responses occurred after 12 weeks for Candida and after 48 weeks for mumps. The magnitude of virologic suppression was correlated with numeric increases in CD4+ T cells, but not with measures of functional immune reconstitution. Plasma virus suppression <100 copies/mL was not significantly correlated with increases in CD4+ T cells or functional immune reconstitution.

Prospective, blinded comparison of laparoscopic ultrasonography vs. contrast-enhanced computerized tomography for liver assessment in patients undergoing colorectal carcinoma surgery

PURPOSE

To prospectively and blindly compare intraoperative laparoscopic ultrasonography to preoperative contrast-enhanced computerized tomography in detecting liver lesions in colorectal cancer patients. Additionally, we compared conventional (open) intraoperative ultrasonography with bimanual liver palpation to contrast-enhanced computerized tomography in a subset of patients.

METHODS

From December 1995 to March 1998, 77 consecutive patients underwent curative (n = 63) or palliative (n = 14) resections for colorectal cancer. All patients undergoing curative resections were randomized to either laparoscopic (n = 34) or conventional (n = 29) surgery after informed consent. All patients underwent contrast-enhanced computerized tomography, diagnostic laparoscopy, and laparoscopic ultrasonography before resection. In those patients who had conventional procedures, intraoperative ultrasonography with bimanual liver palpation was also done. All laparoscopic ultrasonography and intraoperative ultrasonography evaluations were performed by one of two radiologists who were blinded to the CT results. All hepatic segments were scanned using a standardized method. The yield of each modality was calculated using the number of lesions identified by each imaging modality divided by the total number of lesions identified.

RESULTS

In 43 of the 77 patients, both the laparoscopic ultrasonography and CT scan were negative for any liver lesions. In 34 patients, a total of 130 lesions were detected by laparoscopic ultrasonography, CT, or both. When compared with laparoscopic ultrasonography, intraoperative ultrasonography with bimanual liver palpation identified one additional metastatic lesion and no additional benign lesions. laparoscopic ultrasonography identified two patients with mets who had negative preoperative contrast-enhanced computerized tomography.

CONCLUSIONS

Laparoscopic ultrasonography of the liver at the time of primary resection of colorectal cancer yields more lesions than preoperative contrast-enhanced computerized tomography and should be considered for routine use during laparoscopic oncologic colorectal surgery.

Induced tissue integration of bone implants by coating with bone selective RGD-peptides in vitro and in vivo studies

The optimal function of medical implant materials used in tissue substitution is often limited due to its healing properties. This effect is linked to reduced interactions of the implants with the surrounding tissue. Implant surfaces biologically functionalized with arginine-glycine-aspartic acid (RGD) peptides, a class of cellular adhesion factors, are described in this paper. The RGD-peptides are either bound via bovine serum albumin linking on culture plastic dishes as a model surface or via acrylic acid coupling on PMMA surface as a potential implant material. Resulting functionalized surfaces aquire the capability to bind cultured osteoblasts in high levels and show high proliferation rates in vitro. These results are observed for osteoblast cultures as well as from different species with different preparation procedures. A critical minimum distance between the bioactive portion of the RGD-peptides and the implant surface of 3.0-3.5 nm is crucial for the induction of an optimum cell binding process. In vivo animal studies in the rabbit show that newly formed bone tissue generated a direct contact with the RGD-peptide coated implants. In contrast uncoated implants are separated from newly formed bone tissue by a fibrous tissue layer thereby preventing the formation of a direct implant-bone bonding.

Structure investigation of amphiphilic cyclopeptides in isotropic and anisotropic environments-A model study simulating peptide-membrane interactions

It has been proposed that the membrane allows a much more efficient binding of certain small or medium-sized amphiphilic messenger molecules to their receptor, not only by accumulation of the drug, but also by induction of orientations and conformations that are much more favorable for receptor docking than structures adopted in isotropic phases. A series of eight amphiphilic cyclic peptides containing lipophilic (L-alpha-aminodecanoic acid = Ada, L-alpha-aminohexadecanoic acid = Ahd, Nhdg = N-hexadecylglycine) and hydrophilic (Lys, Asp) amino acids were synthesized and examined by means of NMR spectroscopy and molecular dynamics (MD) simulations in isotropic (CDCl3) and membrane-mimicking anisotropic (SDS/H2O) solvents to study the influence of the environment on their individual conformations. NMR data of cyclo(-Gly1-D-Asp2-Ahd3-Ahd4-Asp5-Gly6+ ++-) (C4), cyclo(-Lys1-D-Pro2-Lys3-Ada4-Pro5-Ada6-) (C5) and cyclo(-Lys1-Pro2-Lys3-Ada4-D-Pro5-Ada6-) (C6) clearly indicate that those compounds are too rigid to perform a conformational change upon transition from an isotropic to an anisotropic environment. On the other hand, the experimental data of cyclo (-Gly1-Asp2-Ahd3-Ahd4-Asp5-Gly6-) (C1), cyclo(-Asp1-Ala2-Nhdg3-Ala4-D-Asp5-) (C7), and cyclo(-D-Asp1-Ala2-Nhdg3-Ala4-Asp5-) (C8) suggest highly flexible unstructured molecules in both environments. However, for cyclo(-Asp1-Asp2-Gly3-Ahd4-Ahd5-Gly6-) (C2) we observed a structure inducing effect of a membrane-like environment. The compound populates three different conformations in SDS/H2O, whereas in CDCI3 no preferred conformation can be detected. cyclo(-D-Asp1-Asp2-Gly3-Ahd4-Ahd5-Gly6-) (C3) clearly exhibits two different conformations with a shifted beta,beta-turn motif in CDCI3 and SDS/H2O solutions. The conformational change could be reproduced in a restraint-free MD simulation using the biphasic membrane mimetic CCl4/H2O. Our results give clear evidence that membrane interactions may not only lead to structure inductions, but can also induce major conformational changes in compounds already exhibiting a defined structure in isotropic solution.

Laparoscopic management of colorectal endometriosis

BACKGROUND

In the past, intestinal endometriosis diagnosed at laparoscopy has generally required conversion to conventional surgery. The purpose of this study was to describe the laparoscopic management of colorectal endometriosis at a tertiary referral center.

METHODS

From November 1994 to March 1998, 509 consecutive patients with endometriosis requiring laparoscopic intervention were prospectively evaluated. Those with colorectal involvement were analyzed for stage of disease, procedure, operative time, conversion rate, length of hospitalization, and complications.

RESULTS

In 30 of the 509 patients (5.9%), colorectal involvement was identified. Twenty-eight of these 30 had stage IV disease. Intestinal involvement was suspected preoperatively in 13 of 30. Twelve required superficial excision of colon or rectal endometriomas. Protectomy/proctosigmoidectomy was done in seven cases, and rectal disc excision was performed in five patients. Four cases required conversion due to the overall severity of the pelvic disease. For those who did (n = 12) and did not (n = 18) require full-thickness excisions/resections, the median operative time was 180 min (range, 90-390) and 110 min (range, 45-355), respectively; the median length of hospitalization was 4 days (range, 3-7) and 1 day (range, 0-4), respectively. A major complication occurred in one patient (colovaginal fistula). At a median follow-up of 10 months (range 1-32), 28 patients were improved, and 24 of these had near or total resolution of preoperative symptoms.

CONCLUSIONS

Extensive pelvic endometriosis generally requires rectal disc excision or bowel resection. In our experience, laparoscopic treatment of colorectal endometriosis, even in advanced stages, is safe, feasible, and effective in nearly all patients.

The solution structure of VAT-N reveals a 'missing link' in the evolution of complex enzymes from a simple betaalphabetabeta element

BACKGROUND

The VAT protein of the archaebacterium Thermoplasma acidophilum, like all other members of the Cdc48/p97 family of AAA ATPases, has two ATPase domains and a 185-residue amino-terminal substrate-recognition domain, VAT-N. VAT shows activity in protein folding and unfolding and thus shares the common function of these ATPases in disassembly and/or degradation of protein complexes.

RESULTS

Using nuclear magnetic resonance (NMR) spectroscopy, we found that VAT-N is composed of two equally sized subdomains. The amino-terminal subdomain VAT-Nn (comprising residues Met1-Thr92) forms a double-psi beta-barrel whose pseudo-twofold symmetry is mirrored by an internal sequence repeat of 42 residues. The carboxy-terminal subdomain VAT-Nc (comprising residues Glu93-Gly185) forms a novel six-stranded beta-clam fold. Together, VAT-Nn and VAT-Nc form a kidney-shaped structure, in close agreement with results from electron microscopy. Sequence and structure analyses showed that VAT-Nn is related to numerous proteins including prokaryotic transcription factors, metabolic enzymes, the protease cofactors UFD1 and PrlF, and aspartic proteinases. These proteins map out an evolutionary path from simple homodimeric transcription factors containing a single copy of the VAT-Nn repeat to complex enzymes containing four copies.

CONCLUSIONS

Our results suggest that VAT-N is a precursor of the aspartic proteinases that has acquired peptide-binding activity while remaining proteolytically incompetent. We propose that the binding site of the protein is similar to that of aspartic proteinases, in that it lies between the psi-loops of the amino-terminal beta-barrel and that it coincides with a crescent-shaped band of positive charge extending across the upper face of the molecule.

Intramuscular oxygen partial pressure in the healthy during exercise

The oxygen partial pressure (pO2) in the anterior tibial muscle was measured in n=12 (6 physically active and 6 sedentary) apparently healthy subjects. This was the first time a flexible micro catheter with an outer diameter of 0.45 mm was used during skeletal muscular activity in men. A two level tread mill test which is used in the diagnosis of peripheral arterial occlusive disease was chosen to induce physical stress. In the healthy volunteers a pO2 increase was noted at the beginning of exercise. This was followed by a pO2 decrease because of an increased O2 demand in the working muscle. The initial pO2 increase was thought to be due to the recruitment of capillaries and not the subsequently increased heart rate. At rest and during activity pO2 values were higher in physically active subjects than in the sedentary and the exercise induced decrease of pO2 values was slower and in addition to this the compensation to baseline values quicker.

An efficient strategy for assignment of cross-peaks in 3D heteronuclear NOESY experiments

The question is addressed of how maximal structural NOE data on double labelled proteins can be acquired with a minimal set of NOESY experiments. Two 3D-NOESY spectra are reported which, in concert with other commonly used spectra, provide a convenient strategy for NOE assignment. The 3D CNH-NOESY and 3D NCH-NOESY provide NOE connectivities between amide protons and carbon-bound protons and constitute orthogonal heteronuclear filters which eliminate diagonal signals, considerably improving spectral quality. Two different heteronuclear chemical shift dimensions are recorded in the spectra, thus exploiting the extra dispersion of the heteronucleus and considerably simplifying assignment.

Successful treatment of rectal prolapse by laparoscopic suture rectopexy

BACKGROUND

A wide variety of procedures are used for management of rectal prolapse. The purpose of this study was to evaluate the results of laparoscopic suture rectopexy in the treatment of this condition.

METHODS

From May 1991 to May 1998, 32 consecutive patients were treated by laparoscopic suture rectopexy. In four of them, an additional sigmoid colectomy was performed for refractory constipation or redundant large bowels. The clinical data were analyzed.

RESULTS

Of our 32 patients, 27 were female and five were male. The median age was 51.5 years (range, 20-87). The median operative time was 150 min (range, 90-300), and the median hospital stay was 5 days (range, 2-20). There were no operative mortalities. Three postoperative complications required reoperations for bowel obstructions. At a median follow-up of 33 months (range 3-78), there were two complete recurrences.

CONCLUSIONS

Our experience indicates that laparoscopic suture rectopexy, with and without sigmoid colectomy, is safe, feasible, and effective for the treatment of rectal prolapse.

N-Methylated cyclic RGD peptides as highly active and selective alpha(V)beta(3) integrin antagonists

The alpha(V)beta(3) integrin receptor plays an important role in human tumor metastasis and tumor-induced angiogenesis. The in vivo inhibition of this receptor by antibodies or by cyclic peptides containing the RGD sequence may in the future be used to selectively suppress these diseases. Here we investigate the influence of N-methylation of the active and selective alpha(V)beta(3) antagonist cyclo(RGDfV) (L1) on biological activity. Cyclo(RGDf-N(Me)V-) (P5) was found to be even more active than L1 and is one of the most active and selective compounds in inhibiting vitronectin binding to the alpha(V)beta(3) integrin. Its high-resolution, three-dimensional structure in water was determined by NMR techniques, distance geometry calculations, and molecular dynamics calculations, providing more insight into the structure-activity relationship.

Loss of wild-type MEN1 gene expression in multiple endocrine neoplasia type 1-associated parathyroid adenoma

Multiple endocrine neoplasia type 1 (MEN1) is a human hereditary tumor syndrome characterized by the development of endocrine adenomas of the parathyroid, anterior pituitary, and enteropancreatic tissue. Several lines of evidence have implicated the recently identified MEN1 gene located on chromosome 11q13 as a recessive tumor suppressor gene. Here, we analyzed MEN1 wild-type gene expression in tumors from a large MEN1 kindred. A deletion of codons 227-228 (678del6) located in exon 4 was found in tumor and peripheral blood complementary DNA using a simplified single-strand conformational polymorphism (SSCP) approach well suited for clinical MEN1 mutation screening. The identified 678del6 cDNA mutation deletes a potential phosphorylation site (Tyr227) and corresponds to a germ line mutation co-segregating with disease phenotype in this MEN1 family. Loss of heterozygosity analysis by fluorescent microsatellite PCR showed an exclusive loss of the MEN1 wild-type (and retention of the mutated) allele detectable in DNA from microdissected parathyroid and pancreatic, but not in adrenal, adenomas. Our findings confirm the synergism between MEN1 gene mutations and subsequent MEN1 allelic losses in the tumorigenesis of MEN1-associated adenomas.

HIV infection perturbs DNA content of lymphoid cells: partial correction after 'suppression' of virus replication

OBJECTIVE

To examine the DNA content of circulating lymphocytes obtained from HIV-1-infected persons and to explore the effects of antiretroviral therapy on these indices.

DESIGN

Cross-sectional analysis and 48-week open label treatment trial (AIDS Clinical Trials Group Protocol 315) of zidovudine, lamivudine and ritonavir.

METHODS

Peripheral blood lymphocytes were obtained from HIV-1-infected patients and healthy controls and after 48 h of in vitro cultivation were stained with propidium iodide and analyzed for DNA content by flow cytometry.

RESULTS

HIV-1-infected patients had more hypodiploid cells (19%), fewer G0-G1 phase cells (70%) and more S phase cells (10%) than did healthy controls (8%, 85% and 5% respectively; P = 0.002). Patients with sustained suppression of plasma HIV-1 RNA levels after antiretroviral therapy had only modest improvements in these indices. In contrast, patients who failed to suppress plasma HIV-1 RNA levels had decreases in G0-G1 cells to 54% (P = 0.032) and increases in S phase cells to 24% (P = 0.055). Plasma HIV-1 RNA levels and the percentage of S phase cells were correlated (r, 0.23; P = 0.047). In patients failing antiretroviral therapy, there was an inverse correlation between the percentage of G0-G1 cells and expression of the activation antigens CD38 and HLA-DR on CD4 cells (r, -0.409; P = 0.016) and CD8 cells (r, -0.363; P = 0.035).

CONCLUSIONS

Lymphocytes obtained from HIV-1-infected patients display perturbations in DNA content after brief cultivation in vitro reflective of immune activation in vivo. The marginal improvement in these indices after 'successful' suppression of HIV-1 replication suggests that even low levels of HIV-1 replication are sufficient to induce immune activation and perturbations in DNA content.

Relationship between use of food labels and nutrition knowledge of people with diabetes

PURPOSE

The purpose of this study was to identity how people with diabetes use food labels to manage their intake of specific nutrients, which information is used on the Nutrition Facts label, and the relationship between food label use and nutrition knowledge.

METHODS

A total of 190 individuals participated in this study. Data were collected at six different locations in New Jersey using a four-page questionnaire. Descriptive statistics were employed to assess demographic and clinical characteristics of the participants; chi-square was used to test significance of nominal and ordinal data.

RESULTS

People with diabetes read food label information more often than general consumers; checking sugar content ranked highest. Only 59% of label users referred to the total carbohydrate listings. The level of nutrition knowledge for the majority of participants was "fair" or less, with the remaining scoring "good" and above. The use of nutrition labeling has a limited effect on nutrition knowledge gain.

CONCLUSIONS

Individuals who received most of their information from healthcare providers had a "good" or better nutrition knowledge score. An education program is needed that teaches people how to apply information from the Nutrition Facts label to make healthy food choices.

Increases in T cell telomere length in HIV infection after antiretroviral combination therapy for HIV-1 infection implicate distinct population dynamics in CD4+ and CD8+ T cells

Changes in mean telomeric terminal restriction fragment (TRF) length were examined as a marker for cellular replicative history in HIV-1-infected individuals after institution of anti-retroviral therapy (ART). Increases in mean T cell TRF lengths were observed in most patients following therapy; however, the contribution of individual T cell subsets was complex. An elongation of CD8+ T cell TRF was nearly uniformly observed while changes in mean TRF length in CD4+ T cells were heterogeneous as, despite potent suppression of viral replication, CD4 cell telomeres recovered in some patients, yet continued to decline in others. Increases in CD8 cell TRF correlated with decreased memory cells, suggesting a negative selection in the periphery for CD8 cells with extensive replicative history. In contrast, increases in CD4+ T cell TRF length correlated with increases in naive cell subsets, suggesting that the CD4+ T cell TRF increase may reflect a thymic contribution in some patients. These are the first increases in somatic cell telomere length in a population of cells observed in vivo, and the findings are compatible with therapy-induced reconstitution of the lymphoid compartment with cells having a more extensive replicative potential. These findings further distinguish lymphocytes from other somatic cell populations where only decreases in TRF over time have been noted. Thus, institution of ART in persons with moderately advanced HIV-1 disease reveals distinct population dynamics of CD4 and CD8 T cell subsets and also shows that the lymphocyte replicative history is dynamic.