Immunogenicity of dengue virus type 1 DNA vaccines expressing truncated and full length envelope protein

Recombinant plasmid DNA constructs expressing truncated or full-length dengue-1 envelope (E) with or without the pre-membrane (prM) were tested for immunogenicity in mice, as candidate dengue DNA vaccines. Two plasmids, one expressing the N-terminal 80% E and the other expressing prM and full length E were immunogenic in intradermally inoculated mice. The vaccinated mice produced dengue-1 specific antibodies that were both neutralizing and long lasting. Data suggested that the plasmid expressing prM and full length E produced virus like particles in transfected cells, and is probably a better immunogen compared to that expressing 80% E.     

Effects of mibefradil on uterine contractility

Mibefradil, a benzimidazolyl tetralol derivative, is a new Ca(2+) channel antagonist which is structurally distinct from other Ca(2+) channel antagonists such as nifedipine, verapamil and diltiazem. It is a very effective antihypertensive agent that is thought to achieve its action via a higher affinity block for low-voltage activated (T) than for high-voltage-activated (L) Ca(2+) channels. Nevertheless, it blocks L-type Ca(2+) channels in several tissues. In the present study, the effects of mibefradil on spontaneous rhythmic contractions and on contractions elicited by CaCl(2) (K(+)-depolarized preparations) and oxytocin (in low Ca(2+)/Ca(2+)-free solutions) were investigated on uterus strips from pregnant and non-pregnant rats. Mibefradil (10(-8)-3 x 10(-6) M) caused concentration-dependent inhibition of spontaneous contractions of uterus strips from pregnant and non-pregnant rats with the IC(50) values of 8.83 x 10(-7) M; 5.94 x 10(-7) M (amplitude) and 1.03 x 10(-6) M; 5.48 x 10(-7) M (frequency), respectively. Mibefradil (3 microM) caused a rightward shift in the concentration-response curves for CaCl(2) in K(+) (40 mM)-depolarized uterus strips taken from both pregnant and non-pregnant rats. Mibefradil (3 microM) was, however, more potent for antagonising CaCl(2) responses in uterus strips obtained from pregnant rats than in those from non-pregnant rats. Mibefradil (3 microM) had no effect on oxytocin-induced contraction in Ca(2+)-free physiological salt solution (PSS) on uterus strips from non-pregnant rats. However, it markedly inhibited oxytocin-induced contraction of pregnant rat uterus strips in Ca(2+)-free PSS. Thus, mibefradil probably antagonizes L-type Ca(2+) channels as well as interferes with the intracellular Ca(2+) release mechanism, which would be helpful in the development of a tocolytic agent.     

Induction of bivalent immune responses by expression of dengue virus type 1 and type 2 antigens from a single complex adenoviral vector

There are approximately 100 million new cases of dengue (DEN) virus infection each year. Infection can result in illness ranging from a mild fever to hemorrhaging, shock, or even death. There are four serotypes of dengue virus (DEN1-4), and immunity to one serotype does not cross protect from infection with other serotypes. Currently there are no approved vaccines for dengue fever. In this report, we describe the construction of a bivalent dengue virus vaccine using a complex recombinant adenovirus approach to express multiple genes of DEN1 and DEN2 serotypes. In vaccinated mice, this vector induced humoral immune responses against all four dengue serotypes as measured by enzyme-linked immunosorbent assay. However, the neutralizing antibody responses were specific for DEN1 and DEN2 serotypes. Expansion of this vaccine development platform towards the DEN3 and DEN4 serotypes can lead towards the development of an adenovirus-based tetravalent dengue vaccine.     

Differential susceptibility of cholinergic and noncholinergic neurogenic responses to calcium channel blockers and low Ca2+ medium in rat urinary bladder.

1. The influence of calcium channel blockers and low Ca2+ medium on the neurogenic responses to single pulse electric field stimulation in rat urinary bladder has been examined. 2. Single pulse stimulation evoked a biphasic contractile response consisting of a fast component with a time to peak of 0.72 +/- 0.05 s and a slow component that reached a maximal tension at 2.8 +/- 0.21 s, possibly mediated by two different neurotransmitters. 3. Atropine (3 x 10(-6) M) selectively inhibited the slow component without altering the fast component, suggesting the involvement of cholinergic and non-cholinergic neurotransmitters, respectively. 4. Reducing Ca2+ in the medium to 1/4 of the normal, abolished the slow component of the neurogenic response while the fast contractile response was not altered which may indicate a relatively greater dependence of the cholinergic component on extracellular Ca2+ than the noncholinergic one. 5. The IC50 values for the fast component with respect to verapamil and diltiazem were 1.08 microM and 1.76 microM, respectively. The greater susceptibility of the slow component to calcium channel blockers (IC50 values of verapamil: 0.07 microM and of diltiazem: 0.25 microM) indicates the differential activation of slow calcium channels by the endogenously released substances. 6. Calcium channel blockers inhibited the ATP-induced contraction which was comparable to that of the non-cholinergic component of the neurogenic response suggesting the involvement of ATP as a possible neurotransmitter. 7. Ach-induced contractions were relatively less susceptible to calcium channel blockers and low Ca2+ medium than was the atropine-sensitive cholinergic component of the neurogenic response.     

Influence of hypothyroid state on 45Ca(2+) influx and sensitivity of rat uterus to nifedipine and diltiazem

The influence of methimazole-induced hypothyroidism on spontaneous rhythmic contractions and Ca2+ channel function of rat uterus was examined. Hypothyroidism significantly reduced the amplitude and frequency of spontaneous rhythmic contractions. Nifedipine (10(-12)-10(-6) M) and diltiazem (10(-9)-10(-4) M) caused concentration-related inhibition of the myogenic responses of the oestrogenised rat uterus obtained from both eu- and hypothyroid rats. However, nifedipine was less potent (IC(50); 5.4 x 10(-9) M; n=6) in hypothyroid rat uterus as compared to euthyroid controls (IC(50): 8.13 x 10(-12) M; n=9) to inhibit the rhythmic contractions. Similarly, diltiazem was less potent (IC(50): 4.57 x 10(-6) M; n=9) to inhibit the uterine spontaneous contractions in hypothyroid than in euthyroid rat uterus (IC(50): 6.4 x 10(-8) M; n=6). A similar decrease in the sensitivity to nifedipine and diltiazem for reversal of K+ (100 mM)-induced tonic contraction was observed in uterus obtained from hypothyroid rats compared to the controls. Both nifedipine and diltiazem were less potent for causing concentration-related inhibition of K+-stimulated 45Ca2+ influx in uterine strips taken from the hypothyroid rats. Thus, the IC(50) values of nifedipine (1.83 x 10(-8) M; n=12) and diltiazem (1.8 x 10(-6) M; n=9) were significantly greater in tissues obtained from hypothyroid rats compared to the controls (IC(50) of nifedipine, 1.15 x 10(-11) M; n=12, diltiazem, 8.1 x 10(-8) M; n=8). Nifedipine-sensitive influx of 45Ca2+ - stimulated either by K+ (100 mM) or Bay k8644 (1,4-dihydro-2,6-dimethyl-5-nitro-4-[2'-(trifluromethyl)phenyl]-3-pyridine carboxylic acid methyl ester) (10(-8) M) was significantly less in uterine strips from hypothyroid rats compared to the controls. The results of the present study suggest that the inhibition of uterine rhythmic contractions may be attributable to a reduction in rat myometrial Ca2+ channel function in the hypothyroid state.     

Influence of simultaneous inhibition of cyclooxygenase-2 and inducible nitric oxide synthase in experimental colitis in rats

The inflamed mucosa in ulcerative colitis produces high amount of prostaglandin (PG) and nitric oxide (NO) through inducible enzymes: cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), respectively, implicating them as potential anti-inflammatory drug targets. COX-2 or iNOS-related treatments in different models of colitis have yielded ambiguous results ranging from exacerbation of disease to abolition of inflammation. iNOS and COX-2 induction is blocked by potent anti-inflammatory glucocorticoids, however, serious side effects including relapses limit their usefulness in colitis for long time. Simultaneous inhibition of iNOS and COX-2 was investigated in the current study in 2, 4, 6 trinitrobenzene sulphonic acid (TNBS)-induced colitis in rats. Treatment group received rofecoxib, aminoguanidine hydrochloride or their combination at different doses at 48, 36, 24, 12 and 1 h prior to induction of colitis and 12 h later. Colonic myeloperoxidase (MPO), COX-2, nitrate and nitrite, tumor necrosis factor-α (TNF-α) and lipid peroxidation were maximally reduced by combination of 10 mg/kg rofecoxib and 30 mg/kg of aminoguanidine hydrochloride in TNBS-induced colitis in rats. However, maximum increase in SOD and catalase was noted by this combination. Rats treated with rofecoxib, aminoguanidine hydrochloride and their combinations reduced the inflammation, acute colonic damage produced by TNBS as verified by macroscopic changes in colon. Combination of rofecoxib (10 mg/kg) and aminoguanidine hydrochloride (30 mg/kg) has maximal protective effect on colonic injury induced by TNBS enema which is probably, via mechanism of local inhibition of iNOS and COX-2 activity in colonic mucosa and support the idea that simultaneous inhibition of iNOS and COX-2 inhibitors have a promising potential in the treatment of colitis.     

Rabies in a blind patient: confusion after corneal transplantation

Two blind persons received corneal transplants from a single donor who showed no signs of rabies before he died. One of the recipients, a young girl, died 16 days later of rabies and the other recipient survived. We discuss the possible mode of transmission of rabies to the first recipient and the management of the second recipient.