Modeling the effects of hydroxypropylcellulose in acetaminophen tablet formulation

The objective of the research described here was to develop a set of predictive models that would be used to show the performance of hydroxypropylcellulose as a pharmaceutical tablet binder. A statistically designed set of experiments was used to relate tablet formulation to functionality. It was found that the binder level affected both hardness and dissolution time. Useful predictive models were generated for tablet hardness and dissolution time as a function of the binder or binder-drug ratio. The optimal formulation can be predicted from this study, and will depend upon the combination of desired hardness and the dissolution time for a particular drug.     

Amicrobial pustulosis of the folds. A cutaneous manifestation associated with connective tissue disease

Amicrobial pustulosis (AP) is a recently defined entity associated with connective tissue diseases. Few cases have appeared in the literature. We report a case of AP coexisting with a systemic lupus erythematosus-scleroderma overlap syndrome and marked photosensitivity. The patient presented prominent pustular skin lesions and a few discoid lupus ones. No significant differences in the inflammatory infiltrate were found between the two clinical variants. The infiltrate consisted mainly of CD4+ lymphocytes and many neutrophils. CD1a+ dendritic cells were few in both epidermis and dermis. AP introduces a potential source of diagnostic confusion, but increasing experience of this syndrome will improve the awareness and diagnostic potential among dermatologists.     

The kinetics of bioaccumulation of zinc, copper, lead and cadmium by oysters (Crassostrea iredalei and C. belcheri) under tropical field conditions

Cyanobacterial neurotoxins have been implicated in animal deaths resulting from drinking contaminated water. Anatoxin-a (AN) and homoanatoxin-a (HMAN) have previously been analysed using high-performance liquid chromatography (HPLC) with UV detection, but this procedure is insufficiently sensitive and is subject to interferences. A sensitive fluorimetric (FL) method for determining AN was recently developed using derivatisation with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and this has been applied to the simultaneous determination of AN, HMAN and their epoxy and dihydro degradation products. Microscale syntheses were used to prepare the dihydro and epoxy derivatives from AN and HMAN. These compounds were produced in high yields, as confirmed by electrospray MS and HPLC-FL of their benzoxadiazole derivatives. All six NBD derivatives were readily separated using isocratic reversed-phase HPLC. The recoveries of these compounds from spiked water samples, using weak cation-exchange (WCX) solid-phase extraction (SPE), were 83.2-84.9% at concentrations of 10 micrograms/l. The R.S.D. values were 1.7-3.9% (n = 8) and the limits of detection were better than 10 ng/l for all six compounds, illustrating the high sensitivity of the method. This methodology was successfully applied to the analysis toxin degradation products in natural samples. Dihydroanatoxin-a (0.8 mg/g) was isolated from a benthic Oscillatoria bloom from Caragh Lake, Ireland, and was found to contain two isomers but their ratio was different from that found in the synthetic material.     

A formula for thermal stability (Tm) prediction of PNA/DNA duplexes

An empirical formula for thermal stability (T m) prediction of PNA/DNA duplexes has been derived. The model is based on the T m as calculated for the corresponding DNA/DNA duplex employing a nearest neighbour approach, by including terms for the pyrimidine content and length of the PNA to take into account the increased thermostability of PNA/DNA hybrids and the asymmetry of the PNA-DNA heteroduplex. The predictive power of the T m prediction formula was challenged with an independent data set not used for model building. The T m of >90% of the sequences was predicted within 5 K; 98% of the predicted T ms differ by not more than 10 K from the experimentally determined T m.     

Reduced beta-adrenergic sensitivity in patients with type 1 diabetes and hypoglycemia unawareness

OBJECTIVE: We tested the hypothesis that impaired tissue sensitivity to catecholamines contributes to hypoglycemia unawareness in subjects with type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 21 subjects with type 1 diabetes underwent a standardized insulin infusion protocol to produce a stepwise decrease in plasma glucose to 45-min plateaus of 4.3, 3.6, 3.0, and 2.3 mmol/l. Glycemic thresholds, maximum responses for adrenergic and neuroglycopenic symptoms, and counterregulatory hormones were determined. Patients were classified as hypoglycemia unaware if the initiation of adrenergic symptoms occurred at a plasma glucose level 2 SD below that of nondiabetic volunteers. beta-Adrenergic sensitivity was measured as the dose of isoproterenol required to produce an increment in heart rate of 25 beats per minute above baseline (I25) in resting subjects. RESULTS: Subjects with type 1 diabetes and hypoglycemia unawareness experienced the onset of adrenergic symptoms at a lower plasma glucose level than did those with awareness (2.5+/-0.1 vs. 3.7+/-0.1 mmol/l, P < 0.001), whereas neuroglycopenic symptoms occurred at similar glucose levels (2.7+/-0.2 vs. 2.8+/- 0.1 mmol/l). The plasma glucose levels for counterregulatory hormone secretion (epinephrine 2.9+/-0.2 vs. 4.1+/-0.2 mmol/l; norepinephrine 2.7+/-0.1 vs. 3.2+/-0.2 mmol/l; cortisol 2.5+/-0.2 vs. 3.3+/-0.2 mmol/l, P < 0.01) were also lower in subjects with unawareness. The maximal epinephrine (1,954+/-486 vs. 5,332+/- 1,059 pmol/l, P < 0.01), norepinephrine (0.73 +/- 0.14 vs. 1.47+/-0.21 nmol/l, P = 0.04), and cortisol (276+/-110 vs. 579+/-83 nmol/l, P < 0.01) responses were reduced in the unaware group. I25 was greater in unaware subjects than in subjects without unawareness (1.5+/-0.3 vs. 0.8+/-0.2 microg), where I25 was not different from that of controls (0.8 +/-0.2 microg). CONCLUSIONS: We conclude that subjects with type 1 diabetes and hypoglycemia unawareness have reduced beta-adrenergic sensitivity, which may contribute to their impaired adrenergic warning symptoms during hypoglycemia.     

1,4-Cyclohexanecarboxylates: potent and selective inhibitors of phosophodiesterase 4 for the treatment of asthma

Evaluation of a variety of PDE4 inhibitors in a series of cellular and in vivo assays suggested a strategy to improve the therapeutic index of PDE4 inhibitors by increasing their selectivity for the ability to inhibit PDE4 catalytic activity versus the ability to compete for high affinity [3H]rolipram-binding sites in the central nervous system. Use of this strategy led ultimately to the identification of cis-4-cyano-4-[3-(cyclopentyloxy)-4-methoxyphenyl]cyclohexane-1-carboxyl ic acid (1, SB 207499, Ariflo), a potent second-generation inhibitor of PDE4 with a decreased potential for side effects versus the archetypic first generation inhibitor, (R)-rolipram.     

Influence of dexaminoglutethimide, an optical isomer of aminoglutethimide, on the disposition of estrone sulfate in postmenopausal breast cancer patients

Aminoglutethimide (AG) has been the most widely used aromatase inhibitor in breast cancer patients to date. Commercially, AG (Orimeten) is available as a racemate (DL-AG). Previous studies suggested the stereoisomers of AG (D-AG and L-AG) to differ considerably in their affinities and potencies to inhibit different cytochrome P-450-dependent enzymes, with D-AG being the potent aromatase inhibitor. DL-AG, apart from being an aromatase inhibitor, is known to enhance the metabolism of plasma estrone sulfate (E1S). In the present study we compared the effects of D-AG (500 mg daily) and DL-AG (1000 mg daily) on plasma estrogen levels and estrone (E1) and E1S clearance rates, determined after the injection of [14C]E1 and [3H]E1S, in a cross-over study involving 12 postmenopausal breast cancer patients. Treatment with DL-AG and D-AG suppressed plasma E1S to 18.6% and 15.0% of pretreatment levels, whereas E1 and estradiol E2 levels fell to 18.6% and 23.4% of their pretreatment levels during treatment with DL-AG and to 17.7% and 23.4% during treatment with D-AG, respectively. Thus, both treatment options suppressed all estrogens measured to a similar extent. The clearance rate of E1S increased from a mean pretreatment value of 5.9 to 14.0 and 10.0 L/h during treatment with DL-AG and D-AG, respectively (P < 0.05, comparing the two on-treatment situations), whereas the production rate of E1S decreased from a pretreatment value of 1.44 to 0.64 nmol/h with DL-AG and 0.36 nmol/h with D-AG (P < 0.05, comparing on-treatment values). These findings are consistent with the hypothesis that the D- as well as the L-form of AG may enhance the clearance rate of E1S. The finding of a higher estrogen production rate during treatment with DL-AG compared to D-AG probably reflects an increased plasma level of the estrogen precursor androstenedione (mean levels of androstenedione of 2.54 and 1.27 nmol/L during treatment with D-AG and DL-AG, respectively; P < 0.05).     

The introduction of obstetric forceps in Norway--a 250-year anniversary

Johan Gottfried Erichsen (1713-68), born in Germany and chief medical officer in Bergen from 1747, was probably the first to perform a forceps delivery in Norway, on 14 February 1748. The mother, who had been in labour for five days, survived; the child, however, did not. The obstetric forceps had been a secret in the Chamberlen family and had become more widely known only a few decades earlier. Erichsen, who was the first man-midwife in Norway, had learned obstetrics in Paris by the younger Grégoire. He mastered both the techniques of internal version and forceps delivery. This article describes Erichsen's medical and obstetric background and his qualifications for operative obstetrics. He worked in the period when the obstetric forceps changed obstetrics, birth delivery became an arena also for men, and a part of medicine. Obstetrics was established as a science and physicians had a tool whereby also children could be saved during complicated delivery.