Oral administration of the nucleoside EFdA (4'-ethynyl-2-fluoro-2'-deoxyadenosine) provides rapid suppression of HIV viremia in humanized mice and favorable pharmacokinetic properties in mice and the rhesus macaque.

Like normal cellular nucleosides, the nucleoside reverse transcriptase (RT) inhibitor (NRTI) 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) has a 3'-hydroxyl moiety, and yet EFdA is a highly potent inhibitor of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) replication with activity against a broad range of clinically important drug-resistant HIV isolates. We evaluated the anti-HIV activity of EFdA in primary human cells and in HIV-infected humanized mice. EFdA exhibited excellent potency against HIVJR-CSF in phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs), with a 50% inhibitory concentration of 0.25 nM and a selectivity index of 184,000; similar antiviral potency was found against 12 different HIV clinical isolates from multiple clades (A, B, C, D, and CRF01_AE). EFdA was readily absorbed after oral dosing (5 mg/kg of body weight) in both mice and the rhesus macaque, with micromolar levels of the maximum concentration of drug in serum (Cmax) attained at 30 min and 90 min, respectively. Trough levels were at or above 90% inhibitory concentration (IC90) levels in the macaque at 24 h, suggesting once-daily dosing. EFdA showed reasonable penetration of the blood-brain barrier in the rhesus macaque, with cerebrospinal fluid levels at approximately 25% of plasma levels 8 h after single oral dosing. Rhesus PBMCs isolated 24 h following a single oral dose of 5 mg/kg EFdA were refractory to SIV infection due to sufficiently high intracellular EFdA-triphosphate levels. The intracellular half-life of EFdA-triphosphate in PBMCs was determined to be >72 h following a single exposure to EFdA. Daily oral administration of EFdA at low dosage levels (1 to 10 mg/kg/day) was highly effective in protecting humanized mice from HIV infection, and 10 mg/kg/day oral EFdA completely suppressed HIV RNA to undetectable levels within 2 weeks of treatment.

Medically induced euthyroid hypothyroxinemia may extend survival in compassionate need cancer patients: an observational study.

BACKGROUND: Clinical studies have shown that interventional lowering of serum free thyroxine (FT4) may be associated with extended survival in patients with some terminal cancers. The report of success with this approach in glioblastoma multiforme caused involvement of the author (A.H.) in the prospective consultative management of 23 end-stage solid tumor patients in whom hypothyroxinemia was induced to prolong life. PATIENTS AND METHODS: Patients were self-referred or recommended by attending physicians to the author (A.H.) and had advanced cancers of the brain, ovary, lung, pancreas, salivary gland, and breast or had mesothelioma or soft-tissue sarcoma. Hypothyroxinemia was achieved in euthyroid patients by using methimazole, with the addition of 3,3',5-triiodo-L-thyronine (L-T3) to prevent hypothyroidism and suppress endogenous thyrotropin (TSH). In patients with pre-existent primary hypothyroidism, T3 administration was substituted for T4 replacement. Serum FT4 and TSH concentrations were serially monitored to enable adjustments to drug therapy and prevent clinical hypothyroidism. Survival was measured from the date of hypothyroxinemia induction with T3 or methimazole plus T3. Outcomes were compared with the odds of death based on the Surveillance Epidemiology and End Results and American Joint Committee on Cancer databases and literature reports. RESULTS: The survival time of 83% (19 of 23) of patients exceeded the 20% expected 1-year survival for this hypothyroxinemic, end-stage cancer group. The difference between actual and expected survival was significant. CONCLUSION: Although this is an uncontrolled observational experience with frank limitations, compassionate medical induction of hypothyroxinemia should be considered for patients with advanced cancers to whom other avenues of treatment are closed.

Intracisternal administration of NR2 subunit antagonists attenuates the nociceptive behavior and p-p38 MAPK expression produced by compression of the trigeminal nerve root.

BACKGROUND: We investigated the role of the central NMDA receptor NR2 subunits in the modulation of nociceptive behavior and p-p38 MAPK expression in a rat model with compression of the trigeminal nerve root. To address this possibility, changes in air-puff thresholds and pin-prick scores were determined following an intracisternal administration of NR2 subunit antagonists. We also examined effects of NR2 subunit antagonists on the p-p38 MAPK expression. RESULTS: Experiments were carried out using male Sprague-Dawley rats weighing (200-230 g). Compression of the trigeminal nerve root was performed under pentobarbital sodium (40 mg/kg) anesthesia. Compression of the trigeminal nerve root produced distinct nociceptive behavior such as mechanical allodynia and hyperalgesia. Intracisternal administration of 10 or 20 µg of D-AP5 significantly increased the air-puff threshold and decreased the pin-prick scores in a dose-dependent manner. The intracisternal administration of PPPA (1, 10 µg), or PPDA (5, 10 µg) increased the air-puff threshold and decreased the pin-prick scores ipsilateral as well as contralateral to the compression of the trigeminal root. Compression of the trigeminal nerve root upregulated the expression of p-p38 MAPK in the ipsilateral medullary dorsal horn which was diminished by D-AP5, PPPA, PPDA, but not Ro25-6981. CONCLUSIONS: Our findings suggest that central NMDA receptor NR2 subunits play an important role in the central processing of trigeminal neuralgia-like nociception in rats with compression of the trigeminal nerve root. Our data further indicate that the targeted blockade of NR2 subunits is a potentially important new treatments strategy for trigeminal neuralgia-like nociception.

Beneficial effect of a short-acting NO donor for the prevention of neointimal hyperplasia.

Nitric oxide (NO)-based therapies effectively inhibit neointimal hyperplasia in animal models of arterial injury and bypass grafting, but are not available clinically. We created a simple, effective, locally applied NO-eluting therapy to prevent restenosis after vascular procedures. We investigated the efficacy of perivascular delivery of two distinctly different diazeniumdiolate NO donors, 1-[2-(carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (PROLI/NO) (short half-life) and diazeniumdiolated poly(acrylonitrile) (PAN/NO) (long half-life), in powder or gel form (30% poloxamer 407), at inhibiting neointimal hyperplasia using the rat carotid artery injury model. Two weeks postinjury, all of the NO-eluting therapies successfully reduced neointimal hyperplasia. However, most dramatically, PROLI/NO powder reduced intimal area by 91.2% (p<0.05) versus injury alone. PROLI/NO powder was noted to reduce the medial area (40.2% vs injury alone, p<0.05), whereas other groups showed no such effect. Three days postinjury, each NO treatment group significantly reduced cellular proliferation. However, inflammatory markers revealed a distinct pattern: PAN/NO groups displayed increased leukocyte infiltration (p<0.05), whereas PROLI/NO groups displayed less macrophage infiltration (p<0.05). In conclusion, perivascular delivery of diazeniumdiolate NO donors in powder or gel form effectively inhibits neointimal hyperplasia. Application of short-acting PROLI/NO powder most effectively inhibited neointimal hyperplasia and inflammation and may represent a simple, clinically applicable NO-eluting therapy to prevent neointimal hyperplasia and restenosis after open vascular interventions.

Cancer induction studies using different administrations of benzenediazonium sulfate in mice.

Benzenediazonium sulfate (BD) was administered as 10 weekly subcutaneous injections at 25 micrograms/g b.w. and as 52 weekly oral gavages at 100 micrograms/g b.w. to Swiss mice, starting at 6 weeks of age. The subcutaneous administration induced tumors in the subcutis with an incidence of 8% in females. The oral treatment gave rise to lung tumors with incidences of 52% in females and 62% in males. In the untreated control female mice, no subcutaneous tissue tumor was observed, but the incidences of lung tumors were 28% in females and 38% in males. Histopathologically, the neoplasms were classified as fibrosarcomas of the subcutis and adenomas and adenocarcinomas of the lungs. In an earlier experiment, BD induced high incidences of subcutaneous tissue tumors in the same species when it was administered as 26 weekly subcutaneous injections at 10 micrograms/g. This indicates the length of treatment is paramount to the dose of carcinogen. The oral route, even though it was carcinogenic in the lungs, failed to elicit the development of cancer in the glandular stomach.

Quantitative morphometric analysis of pulmonary deposition of aerosol particles inhaled via intratracheal nebulization, intratracheal instillation or nose-only inhalation in rats.

The effectiveness of three techniques to deliver a diazo dye suspension into the lungs of rats was compared. The intratracheal nebulization (ITN) technique delivered 10 microl of the suspension per 5-ml puff of air in 10 puffs as an aerosol. The intratracheal fast instillation (ITFI) technique delivered 100 microl of the suspension in a single 2-ml puff of air as droplets. The nose-only inhalation (NI) technique aerosolized the suspension at an analytical concentration that provided a calculated dose equivalent to 100 microl of the suspension in a 2-h inhalation period. Immediately after dosing, all the rats were killed by exsanguination. The trachea was tied and the lung was inflated in situ with air. After fixation, 5-microm thick slices were prepared from each lobe of the lung at a plane perpendicular to the axis of the lobar bronchus at levels proximal, medial and distal to the hilus. The numbers of bronchi, bronchioli and alveolar ducts within four ranges of diameters and the proportion of each selected area of lung tissue with and without dye particles were quantified using electronic imaging analyzers. The results indicated that ITN and ITFI dispersed the particles evenly throughout most of the airways and in patches in the alveoli. The NI technique dispersed the particles homogeneously throughout the airways and the alveoli in the lungs. The mean number-percentage and the mean area-percentage data revealed that the doses delivered by ITN and NI were approximately 60% and 10%, respectively, of the ITFI dose. Thus, the ITFI technique appeared to be most suitable for pulmonary absorption and disposition studies where dosage precision is of primary concern. The ITN technique would need further improvement to meet the requirements for dose precision and particle distribution. For both ITFI and ITN, particle size was apparently not a critical determinant for deposition. The NI technique is suitable for inhalation toxicity studies where the pattern and uniformity of particle deposition is the primary concern.

Skin tumours induced by local and systemic action of N-nitroso-compounds in rats.

The skin of white outbred rats was painted with solutions of N-methyl-N-nitrosourea (MNU), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), N-methyl-N,N'-dinitroguanidine and diazoacetic ester (DAAE). DAAE was administered to rats intravenously, intraperitoneally and subcutaneously as well. Skin tumours have appeared only in the experiments with MNU, MNNG and DAAE. The application of MNU and MNNG caused tumours of the skin in the site of application, and as for DAAE, it induced tumours in the remote places of the skin. Systemic methods of DAAE administration entailed mainly mammary tumours in female rats, but not those of the skin. Possible mechanisms of action of the compounds under study have been discussed.

[Diazane resistance of leukemia L1210 strain: obtaining and kinetic characteristics of growth]. / Rezistentnyi diazanu shtamm leikemii L1210. Poluchenie i kineticheskaia kharakteristika rosta.

The diazane (1-2-bis diazoacetylene) resistant strain was obtained by consecutive transplantation of leukemia L 1210 cell from mice, treated by subtherapeutic doses of the drug. The kinetic pattern of development of the primary and resistant strain were analogous. The resistant strain differed from the primary one by a less rate of the growth and more persistant course. Death of mice in both strains occurred under gaining similar thershold number of cells. In both strains a linear dependence was noted between the survival of mice and the logarithm of the transplanted cells number. The time of doubling of the total number of leukemic cells in the organism of mice in the resistant strain was twice as that in the primary one.