Nano-hydroxyapatite improves intestinal absorption of acetazolamide (BCS Class IV drug)–but how?

We earlier reported that coating poorly water-soluble drugs with nano-hydroxyapatite (nano-HAP) improves bioavailability after oral administration. In the present study, we coated BCS Class IV drug acetazolamide (AZ) with nano-HAP (AZ/HAP formulation), and investigated its bioavailability and nano-HAP’s role in promoting it. We tested AZ bioavailability after a single oral dose of the AZ/HAP formulation in rats, followed by a series of in vitro, ex vivo and in vivo testing. The binding state of AZ and nano-HAP was analyzed by gel filtration chromatography. AZ permeability was studied using a Caco-2 cell monolayer assay kit, to test for tight junction penetration, then using an Ussing chamber mounted with intestinal epithelium, both with and without Peyer’s patch tissue, to examine the role of intracellular transport. Fluorescence-labeled nano-HAP particles were administered orally in rats to investigate their localization in the intestinal tract. The area under the blood concentration time-curve in rats was about 4 times higher in the AZ/HAP formulation group than in the untreated AZ group. Gel filtration analysis showed AZ and nano-HAP were not bound. The Caco-2 study showed equivalent AZ permeability for both groups, but without significant change in transepithelial electrical resistance (TEER), indicating that tight junctions were not penetrated. In the Ussing chamber study, no significant difference in AZ permeability between the two groups was observed for epithelium containing Peyer’s patch tissue, but for epithelium without Peyer’s patch tissue, at high concentration, significantly higher permeability in the AZ/HAP formulation group was observed. Fluorescent labeling showed nano-HAP particles were present in both intestinal villi and Peyer’s patch tissue 30 min after oral administration. Our results suggest that nano-HAP’s enhancement of drug permeability from the small intestine occurs not via tight junctions, but intracellularly, via the intestinal villi. Further study to elucidate the mechanism of this permeability enhancement is required.

Hospital referrals with possible ectopic pregnancy: prospective observational study

Women of reproductive age with abdominal pain represent a diagnostic challenge, especially in primary care where the decision whether to refer to hospital needs to be taken. The diagnosis of an ectopic pregnancy hinges on a combination of clinical findings and a positive urinary pregnancy test (UPT). We investigated whether non-pregnant patients with abdominal pain were being referred inappropriately to hospital to exclude ectopic pregnancy because a UPT had not been performed or had been interpreted incorrectly. In this study, of the 81 patients referred by their general practitioners (GPs) on suspicion of ectopic, 38 were not pregnant on admission and only 46% of the UPT results in hospital agreed with those reported to the GP by the patient prior to referral. Given the high sensitivity and specificity of correctly interpreted UPTs, our findings suggest that pregnancy should be confirmed before hospital referral.

Microvascular vasodilator response to acetylcholine is increased in women with pre-eclampsia

OBJECTIVES

To evaluate in vivo microvascular responses to incremental doses of the endothelial-dependent vasodilator, acetylcholine, and the endothelial-independent vasodilator, sodium nitroprusside, in women with pre-eclampsia and gestation-matched normotensive pregnant controls.

DESIGN

Prospective clinical study.

SETTING

Southern Derbyshire Acute Hospitals Trust, and University of Nottingham Division of Vascular Medicine.

POPULATION

Thirteen women with pre-eclampsia and 16 normotensive pregnant controls.

METHODS

Cutaneous microvascular vasodilator responses to iontophoretic administration of incremental doses of acetylcholine and sodium nitroprusside (25-100 microC) were evaluated under temperature-controlled conditions using laser Doppler fluximetry.

RESULTS

Resting skin temperature and blood flow were similar among 13 women with pre-eclampsia [mean blood pressure 151/93 mmHg (4/3); mean gestation 35.6 weeks (1.0); and mean proteinuria 1.1 g/24h (0.2)] and 16 normotensive pregnant controls [mean blood pressure 111/63 mmHg (2/2); mean gestation 34.3 weeks (0.9)]. Peak vasodilator responses to acetylcholine were increased in women with pre-eclampsia (median flux ratio 15.1 [IQR 12.3-17.6] vs 11.7 [IQR 8.4-12.6], P < 0.05), whereas sodium nitroprusside responses were not different between the two groups: 11.4 [IQR 8.6-13.4] vs 9.5 [IQR 8.0-12.3].

CONCLUSION

In vivo microvascular vasodilator responses to acetylcholine are increased in women with pre-eclampsia, while endothelial-independent vasodilation is unchanged. Although the mechanism of acetylcholine induced vasodilation in small vessels is unclear, this study confirms previous animal data and provides in vivo evidence of altered microvascular endothelial cell function in pre-eclampsia.

The preliminary characterization of a vasoactive circulating factor(s) in preeclampsia

OBJECTIVE

The endothelium-dependent behavior of myometrial resistance vessels from women with preeclampsia differs dramatically from that of healthy pregnant women. Similar functional changes may be induced in vessels from healthy pregnant women by incubation with plasma from women with preeclampsia.

STUDY DESIGN

Myometrial arterioles, obtained from healthy pregnant women at elective cesarean section, were incubated with plasma from women with preeclampsia or plasma from healthy pregnant women. Myographic techniques were used to study the endothelium-dependent relaxation to bradykinin. The effects of subjecting plasma from women with preeclampsia to heat treatment, charcoal stripping, protein extraction and digestion, and column fractionation on the inducible changes in endothelial function were likewise investigated.

RESULTS

Incubation with plasma from women with preeclampsia resulted in a significant reduction in the vessel's endothelium-dependent relaxation, a change that was reversible. This effect was reduced by heat treating and charcoal stripping, maintained within a plasma protein concentrate, and completely removed by protease digestion. The vasoactive component(s) of the plasma had a molecular weight greater than 100 kd.

CONCLUSIONS

Plasma of women with preeclampsia alters the endothelium-dependent relaxation of myometrial vessels. Our findings suggest that such alterations are induced by a high-molecular-weight protein/glycoprotein, with possible contributions from a hydrophobic, lipophilic factor.

Inducible change in the behavior of resistance arteries from circulating factor in preeclampsia: an effect specific to myometrial vessels from pregnant women

OBJECTIVE

It has previously been observed that a circulating factor or factors may be responsible for the changes in vessel behavior that are postulated to underlie the pathogenesis of preeclampsia. We wished to ascertain whether such changes in endothelial function are dependent on the vascular bed under investigation.

STUDY DESIGN

Myometrial and infracolic omental vessels resistance vessels were obtained at cesarean delivery or hysterectomy. After incubation with either plasma from women with preeclampsia or plasma from normotensive pregnant women, myographic techniques were used to assess the endothelium-dependent relaxations of these vessels.

RESULTS

Incubation of myometrial vessels from normotensive pregnant women with plasma from women with preeclampsia resulted in a significant reduction in endothelium-dependent relaxation, an effect that was independent of the parity of the patients from whom the vessels had been taken. Incubation of omental vessels from normotensive pregnant women and myometrial vessels from nonpregnant women with plasma from women with preeclampsia had no effect on the endothelium-dependent relaxation observed.

CONCLUSIONS

This study demonstrates that the inducible changes in resistance vessel behavior are dependent on the tissue bed under investigation and on the pregnancy status of the patient.

Botulinum toxin type A therapy for palmar and digital hyperhidrosis

OBJECTIVE

We evaluated the efficacy of subepidermal injections of botulinum toxin type A on recalcitrant palmar and digital hyperhidrosis.

METHODS

Twenty patients with recalcitrant palmar and digital hyperhidrosis were treated with subepidermal injections of botulinum toxin. Nineteen patients completed the 12-month study. Injections were performed in 3 stages. The total dose of toxin for each hand, which included the palm, thenar eminence, and digits, was 165 units. Patients were followed up on a monthly basis.

RESULTS

Botulinum toxin significantly reduced sweat production in the treated areas. Anhidrosis lasted 9 months in 3 patients, 8 months in 3 patients, 7 months in 8 patients, 6 months in 3 patients, 5 months in 1 patient, and 4 months in 1 patient. Reduced sweating of the palm and digits continued in all patients for the 12-month evaluation period, with the greatest reduction of sweating in the nondominant hand. Mild weakness of the thumb occurred in 4 patients at a mean duration of 3 weeks, with the greatest duration being 6 weeks.

CONCLUSION

Botulinum toxin provides a safe and efficacious alternative in the treatment of recalcitrant palmar and digital hyperhidrosis.

Desmin as a possible immunohistochemical marker for feline hypertrophic cardiomyopathy

Desmin has been suggested as a possible histopathological marker for hypertrophic cardiomyopathy (HCM) in humans. To test whether a similar pattern of desmin staining applies to HCM in cats, we conducted an immunohistochemical study on myocardial samples from 13 cats (HCM 4, other cardiomyopathies (OCM) 4, and control 5). The pattern of staining for desmin in HCM cats was not the same as that reported in humans, but was weaker than in OCM cats and controls. This suggested that desmin may be a possible histochemical marker for feline HCM, but our data was insufficient to clearly confirm this.

Plasma from women with pre-eclampsia induces an in vitro alteration in the endothelium-dependent behaviour of myometrial resistance arteries

OBJECTIVE

To compare the in vitro effect of plasma from normal pregnant women and women with pre-eclampsia on the endothelium-dependent behaviour of myometrial resistance arteries from normal pregnant women.

DESIGN

An in vitro comparative study.

SETTING

Nottingham City Hospital.

SAMPLE

Uterine biopsy specimens were obtained from normal pregnant women delivered by elective caesarean section at term. Plasma was collected from nulliparous women with pre-eclampsia (n = 18), and from multiparous normal pregnant women (n = 18), all samples being matched for maternal age and gestation at venepuncture. Pools of plasma from women with pre-eclampsia and normal pregnant women were formed from these samples and were used in all the experiments.

METHODS

Myometrial resistance vessels obtained from the uterine biopsies were incubated with normal pregnant plasma, plasma from women with pre-eclampsia, or without plasma. Wire myography was employed to study the effect of plasma on the endothelium-dependent behaviour of these vessels.

RESULTS

Incubation of vessels from normal pregnant women with plasma from women with pre-eclampsia resulted in a significant reduction in endothelium-dependent relaxation, compared with vessels incubated either with plasma from normal pregnant women or without plasma. This alteration in endothelial function occurred after an incubation period of one hour and required a threshold concentration for its effect to become established. Removal of the vascular endothelium abolished these changes in vessel behaviour. There were no plasma-induced alterations in the endothelium-independent behaviour of the vascular smooth muscle.

CONCLUSIONS

This study supports the hypothesis that plasma from women with pre-eclampsia is capable of altering endothelium-dependent myometrial relaxation in vessels from pregnant women.

VEGF via VEGF receptor-1 (Flt-1) mimics preeclamptic plasma in inhibiting uterine blood vessel relaxation in pregnancy: implications in the pathogenesis of preeclampsia

Preeclampsia is a multisystem disorder characterized by hypertension and proteinuria. There is accumulating evidence that this is a disease of the endothelium, with an as-yet unidentified circulating factor, or factors, causing the observed alteration in vascular function. We previously reported that the function of myometrial vessels is altered on exposure to plasma from women with preeclampsia. Vascular endothelial growth factor (VEGF) is an angiogenic growth factor that acts via two high-affinity receptors (KDR and Flt-1), and its production is increased in preeclampsia. Here we report that VEGF and its Flt-1 receptor may play a pivotal role in the altered vascular function of preeclampsia. Myometrial resistance vessels were obtained at the time of cesarean section. Using the Mulvany wire myograph, the endothelium-dependent behavior of these vessels was studied. Incubation of vessels from pregnant women with VEGF resulted in a reduction of endothelium-dependent relaxation that mimicked the reduction induced by plasma from women with preeclampsia. The altered function that occurred upon exposure of vessels to VEGF or plasma from women with preeclampsia did not occur when plasma was incubated with antibodies to VEGF before vessel incubation. The presence of an anti-KDR receptor antibody had no effect on VEGF response. However, in the presence of an anti-Flt-1 receptor antibody, VEGF or plasma from women with preeclampsia no longer attenuated the endothelium-dependent relaxation (p < 0.05). The changes observed with VEGF and plasma from women with preeclampsia and their subsequent blockade with anti-VEGF antibody and anti-Flt-1 receptor antibody strongly suggest that VEGF acting through the Flt-1 receptor is pivotal in the pathogenesis of this disease.

Angiotensin-converting enzyme insertion-deletion polymorphism in normotensive and pre-eclamptic pregnancies

OBJECTIVE

To investigate the hypothesis that pre-eclampsia is associated with a common insertion-deletion polymorphism in the angiotensin-converting enzyme gene.

DESIGN

Seventy-two women with pre-eclampsia and 83 normotensive pregnant women participated in the study. Pre-eclampsia was defined as a blood pressure exceeding 140/90 mm Hg in a previously normotensive woman, associated with proteinuria in excess of 300 mg/l in a 24 h collection. Samples for fetal genotyping were available from 66 pregnancies complicated by pre-eclampsia and 79 normotensive pregnancies.

METHODS

Maternal and fetal samples were genotyped at the insertion-deletion (I-D) polymorphism in intron 16 of the angiotensin-converting enzyme gene by the polymerase chain reaction followed by agarose electrophoresis.

RESULTS

Neither the I-D genotype distributions nor the allele frequencies differed significantly between pre-eclamptic and normotensive pregnancies in maternal or fetal samples (phi2 <0.3, not significant). The odds ratio for pre-eclampsia in women with the DD genotype, compared with the ID and II genotype, was 1.09 (95% confidence interval 0.55-2.16). The odds ratio associated with the DD genotype in the fetus was 1.14 (0.56-2.32).

CONCLUSION

This study has found no evidence that the insertion-deletion polymorphism in the angiotensin-converting enzyme gene is associated with pre-eclampsia.

Targeted disruption of SMAD3 results in impaired mucosal immunity and diminished T cell responsiveness to TGF-beta

SMAD3 is one of the intracellular mediators that transduces signals from transforming growth factor-beta (TGF-beta) and activin receptors. We show that SMAD3 mutant mice generated by gene targeting die between 1 and 8 months due to a primary defect in immune function. Symptomatic mice exhibit thymic involution, enlarged lymph nodes, and formation of bacterial abscesses adjacent to mucosal surfaces. Mutant T cells exhibit an activated phenotype in vivo, and are not inhibited by TGF-beta1 in vitro. Mutant neutrophils are also impaired in their chemotactic response toward TGF-beta. Chronic intestinal inflammation is infrequently associated with colonic adenocarcinoma in mice older than 6 months of age. These data suggest that SMAD3 has an important role in TGF-beta-mediated regulation of T cell activation and mucosal immunity, and that the loss of these functions is responsible for chronic infection and the lethality of Smad3-null mice.

Targeted disruption of SMAD3 results in impaired mucosal immunity and diminished T cell responsiveness to TGF-beta

SMAD3 is one of the intracellular mediators that transduces signals from transforming growth factor-beta (TGF-beta) and activin receptors. We show that SMAD3 mutant mice generated by gene targeting die between 1 and 8 months due to a primary defect in immune function. Symptomatic mice exhibit thymic involution, enlarged lymph nodes, and formation of bacterial abscesses adjacent to mucosal surfaces. Mutant T cells exhibit an activated phenotype in vivo, and are not inhibited by TGF-beta1 in vitro. Mutant neutrophils are also impaired in their chemotactic response toward TGF-beta. Chronic intestinal inflammation is infrequently associated with colonic adenocarcinoma in mice older than 6 months of age. These data suggest that SMAD3 has an important role in TGF-beta-mediated regulation of T cell activation and mucosal immunity, and that the loss of these functions is responsible for chronic infection and the lethality of Smad3-null mice.

Preeclampsia: the endothelium, circulating factor(s) and vascular endothelial growth factor

It has been proposed that endothelial cell activation is the primary event in the multisystem disorder of preeclampsia. Evidence for endothelial involvement in this condition abounds. The best-characterized morphologic abnormality of this syndrome, glomerular endotheliosis, involves endothelial cells. Also associated with preeclampsia is a loss of endothelial cell integrity, with the consequent increase in vascular permeability, and an increase in the circulating levels of the endothelial cell markers, fibronectin, von Willebrand factor, tissue plasminogen activator, and plasminogen activator inhibitor-1. It is now well documented that endothelial activation contributes to the coagulation abnormalities observed in this disease. There is much evidence that the endothelial alterations in preeclampsia result from one or more circulating factors. The incubation of cultured endothelial cells with serum or plasma samples, taken from normal pregnant women and women with preeclampsia, results in marked alterations in cell behavior and metabolic processes. More recently, experiments employing myographic techniques have demonstrated convincingly the effects of a circulating factor(s) on the function of endothelial cells of resistance arteries. Vascular endothelial growth factor (VEGF) possesses many of the characteristics required of a candidate circulating factor. It contains a hydrophobic secretory signal sequence, exerts in vitro effects specific to vascular endothelial cell, and promotes endothelial expression of procoagulant activity. Circulating VEGF concentrations are elevated in women with preeclampsia, and VEGF increases microvascular endothelial cell prostacyclin production in a dose-dependent manner, analogous to the acute effects of plasma from patients with preeclampsia. Similarly, in myographic studies, when myometrial resistance arteries are incubated with VEGF, there are dose-dependent alterations in endothelium-dependent behavior, mirroring those found after incubation with plasma from patients with preeclampsia.