Clinics in diagnostic imaging (4). Renal angiomyolipoma with spontaneous perinephric haemorrhage

A 69-year-old Chinese woman presented with acute right-sided abdominal pain. Intravenous urogram and ultrasound demonstrated a fatty lower renal pole mass with a perinephric collection. The diagnosis of renal angiomyolipoma was confirmed by computerised tomography. The perinephric haemorrhage resolved with conservative treatment. The classification, clinical features and management of this entity is discussed. The role of imaging in diagnosis and follow-up of renal angiomyolipoma is emphasised.

K-channel opening activity of ZD6169 and its analogs: effect on 86Rb efflux and 3H-P1075 binding in bladder smooth muscle

Zeneca ZD6169, (S)-N-(4-benzoylphenyl)-3,3,3-trifluoro- 2-hydroxy-2-methylpropionamide, is a novel compound which relaxes urinary bladder smooth muscle in vitro. The effect of ZD6169 and two of its analogs on 86Rb efflux and 3H-P1075 binding in guinea pig bladder strips was investigated to characterize the K-channel opening properties of this compound. ZD6169 concentration dependently increased the rate of 86Rb efflux from guinea pig bladder strips. 86Rb efflux evoked by ZD6169 and its analogs was blocked by glibenclamide (30 muM) but not by charybdotoxin, apamin or alpha-dendrotoxin, suggesting that this compound activates KATP channels in guinea pig bladder. In addition, interaction of ZD6169 with KATP channels was also confirmed in human bladder smooth muscle cells. Specific binding of 3H-P1075, a potent opener of KATP channels, to guinea pig urinary bladder strips was observed. 3H-P1075 binding was inhibited by known KATP openers. ZD6169 inhibited binding of 3H-P1075 to urinary bladder strips like other structurally different KATP openers, e.g. cromakalim and pinacidil. Potencies for inhibition of 3H-P1075 binding by ZD6169 and other potassium channel openers correlate well with potencies for increase in 86Rb efflux and bladder muscle relaxation studies. It is concluded that Zeneca ZD6169 is a potassium channel opener which activates ATP-sensitive K-channels in guinea pig urinary bladder strips as well as in human bladder cells. Furthermore, binding studies suggest that the effects of ZD6169 and its analogs are mediated by binding to the site labeled by 3H-P1075 in guinea pig bladder strips.

Dementia and physical disability as competing risks for mortality in a community-based sample of the elderly Japanese

To examine whether an excess mortality due to dementia is independent of coexisting physical disability, a probability-sample of the non-institutionalized elderly (n = 3,308) living in Sendai City, Japan was followed between 1988 and 1991. Of those, 128 were diagnosed as dementia in 1988 by psychiatrists, using Diagnostic and Statistical Manual of Mental Disorders, Third Edition-Revised as a diagnostic standard. Information on the ability to perform activities of daily living (ADL) was collected by self-report of the study subjects in 1988 baseline survey. The survival status was investigated three years later. The risks of dementia and co-existing ADL disability for mortality was examined by Cox proportional hazard models. The results indicated that the relation between dementia and mortality was two-fold, depending upon the physical functions. Dementia increased the risk for mortality among those without ADL disability, but it did not so among those with ADL disability, rather ADL function was a stronger predictor for mortality among the latter individuals. Prevention and treatment of physical disability would be important for improving the survival of the demented people.

Zeneca ZD6169 and its analogs from a novel series of anilide tertiary carbinols: in vitro KATP channel opening activity in bladder detrusor

The potassium (K+) channel opening activity of Zeneca ZD6169 and one of its pyridylsulfonyl analogs from the anilide tertiary carbinol series was ascertained. Their mechanoinhibitory effects on the myogenic activity of the guinea pig bladder detrusor muscle were measured in a set of functional assays. Elevating the K+ concentration in the tissue bath from 15 to 80 mmol/l increased the IC50 value of ZD6169 from 1.61 +/- 0.22 223 +/- 37 mumol/l. This result suggests that ZD6169 may act as a K+ channel opener. Similar to the prototypic ATP-sensitive K+ (KATP) channel opener cromakalim, the K+ channel openers from the anilide tertiary carbinol series displayed stereoselective mechanoinhibitory activity only in the test protocol in which the detrusor was stimulated with 15 mmol/l KCl. Being the active enantiomer, ZD6169 has an activity more than 30-fold higher than the less active enantiomer. ZD6169 at 10 mumol/l hyperpolarized the guinea pig detrusor membrane potential by 6.1 +/- 1.2 mV and increased the whole cell KATP current in isolated guinea pig smooth muscle cells by 34.9 +/- 7.9 pA. This is comparable to the increase of 26.8 +/- 5.0 pA obtained with 10 mumol/l of lemakalim, the active enantiomer of cromakalim. The K+ channel opening activity of ZD6169 and the pyridylsulfonyl analog was competitively antagonized by the KATP channel blocker glibenclamide in the guinea pig detrusor with a pA2 value of 7.2. This activity, however, was unaffected by blockers of small and large conductance Ca-dependent K+ channels, such as apamin and charybdotoxin, respectively. The present study showed that Zeneca ZD6169 and its analog from the anilide tertiary carbinol series are K+ channel openers that activate KATP channels in vitro to relax bladder detrusors.

Potent, orally active, competitive N-methyl-D-aspartate (NMDA) receptor antagonists are substrates for a neutral amino acid uptake system in Chinese hamster ovary cells

A series of enantiomerically pure (phosphonomethyl)-substituted phenylalanine derivatives related to SDZ EAB 515 (1) were prepared as competitive N-methyl-D-aspartate (NMDA) receptor antagonists. Unlike most known competitive NMDA antagonists, analogs in this series with the S-configuration are potent NMDA antagonists whereas analogs with the unnatural R-configuration are weak NMDA antagonists, as determined by receptor binding experiments and their anticonvulsant action in mice. Examination in a previously reported competitive NMDA pharmacophore model revealed that receptor affinity can be explained partially by a cavity that accommodates the biphenyl ring of 1, while the biphenyl ring of the R-enantiomer 2 extends into a disallowed steric region. We proposed that analogs with the natural S-configuration and a large hydrophobic moiety would have an advantage in vivo over analogs with an R-configuration by being able to use a neutral amino acid uptake system to enhance both peripheral adsorption and transport into the brain. Examination in a system L neutral amino acid transport carrier assay shows that 1 competes with L-Phe for transport in an apparent competitive and stereospecific manner (estimated Ki = 50 microM). The 1- and 2-naphthyl derivatives 3a,3b were found to be among the most potent, competitive NMDA antagonists yet discovered, being ca. 15-fold more potent than 1 in vitro and in vivo, with a long duration of action. The title compound 3a had potent oral activity in MES (ED50 = 5.0 mg/kg). 3a also retains its ability to compete, albeit more weakly than 1 (estimated Ki = 200 microM), for L-Phe uptake to CHO cells. In this series, analogs with the R-configuration are not substrates for the system L neutral amino acid transport carrier. These results provide evidence that central nervous system active agents can be designed as substrates of a neutral amino acid transporter as a means to enhance penetration of the blood-brain barrier.

K-channel opening activity of dihydropyridine ZM244085: effect on 86Rb efflux and 3H-P1075 binding in urinary bladder smooth muscle

Zeneca ZM244085, 9-(3 cyanophenyl)hexahydro-1,8 acridinedione, is a novel dihydropyridine (DHP) which relaxes KCl precontracted urinary bladder smooth muscle in vitro. The effect of ZM244085 on low and high KCl induced contractions, 86Rb efflux and [3H]-P1075 binding in guinea pig bladder strips was investigated to characterize the K-channel opening properties of this compound. Since ZM244085 is a dihydropyridine its effect on DHP binding sites on Ca2+ channels was also investigated. ZM244085 was found to be more potent in relaxing detrusor strips precontracted with 15 mM KCl than strips precontracted with 80 mM KCl (Li et al., 1995). This functional profile of ZM244085 is similar to that exhibited by typical K-channel openers (PCO). In addition, inhibition of ZM244085 induced relaxation of detrusor strips by glibenclamide suggests that ZM244085 opens ATP sensitive K-channel (KATP) in urinary bladder (Li et al., 1995). Since the glibenclamide sensitive smooth muscle relaxation activity of ZM244085 could still be an indirect effect of this compound on KATP channels we carried out 86Rb efflux studies and [3H]-P1075 binding studies to further confirm these findings. The 86Rb efflux assay is a direct method for monitoring the movement of K+ ions across the cell membranes. Displacement of [3H]-P1075 binding to bladder membranes supports a direct action of the compound on the KATP channel. The present study demonstrates that ZM244085 in a concentration dependent manner increases the rate of 86Rb efflux from guinea pig bladder strips. This effect was inhibited by glibenclamide (30 microM), a known KATP channel blocker. In addition, interaction of ZM244085 with KATP channels was also confirmed in human bladder smooth muscle cells using a 42K efflux assay. Furthermore, we were able to demonstrate that ZM244085, structurally distinct PCO, inhibited the binding of 3H-P1075 to urinary bladder strips in a manner similar to other KATP openers such as cromakalim and pinacidil. Inhibition of 3H-P1075 binding by ZM244085 and other PCO's correlates well with increases in 86Rb efflux and bladder muscle relaxation studies. Finally, ZM244085 did not exhibit any significant affect on VSCC as evidenced by very weak inhibition of [3H]-PN200,110 binding to bladder membranes by ZM244085. It is concluded that Zeneca ZM244085 is a PCO which activates KATP channels in urinary bladder.

Aerosol particle microphotography and glare-spot absorption spectroscopy

The relative intensities of glare spots in the image of an electrodynamically trapped aerosol droplet are measured experimentally with an aerosol particle microscope and calculated theoretically. The theoretical calculations are in good agreement with these experiments and indicate that the intensities of these spots are extremely sensitive to the imaginary part of the refractive index. Experimentally, we obtain the molecular absorption spectrum of an impurity within a droplet by recording the spectrum of an individual glare spot produced by broadband illumination.

Determination of free digoxin in sera of 8 patients with chronic cardiac insufficiency

AIM

To establish a method for the determination of free digoxin in serum for clinical use and to study the relationship between the free and total digoxin concentrations in chronic cardiac insufficiency patients receiving digoxin with different renal function.

METHODS

The ultrafiltration with fluorescence polarization immunoassay was used to determine the concentration of free digoxin.

RESULTS

The concentrations of digoxin standards in serum were 0.96, 1.92, and 3.84 nmol.L-1. The relative standard deviation was < 7% for intra-day and < 6% for inter-day determinations. The average recovery was 99.95 +/- 2.18%. The ratio of free/total digoxin in chronic cardiac insufficiency patients with renal dysfunction was lower than that in patients with normal kidneys (63.5 +/- 4.7% vs 75.1 +/- 3.9%, P < 0.01).

CONCLUSION

The present method is simple and reliable. In these patients there is an over-measurement for total digoxin concentration, suggesting the presence of elevated endogenous digoxin-like immunoreactive substances.

Measuring the transport mean free path using a reference random medium

The transport mean free path of microwave radiation in a random sample is determined from measurements of transmission through a composite sample of the medium with unknown scattering characteristics and a random medium of variable thickness and known scattering parameters. The method can be applied at optical frequencies by use of a ceramic wedge as the medium of variable thickness.

[Research on corneal thickness at multi-points in normal and myopic eyes]

The corneal thickness of the center and other 24 points were measured in 31 normal eyes and 246 myopic eyes. The results show that the mean central corneal thickness of the normal eye is 541 +/- 45.29 microns and that of the myopic eye, 544 +/- 35.01 microns. There are no significant differences in the central corneal thickness in comparisons between the left and right eye, between the male and female, among various age groups, and among various degrees of refractive error. However, with the increase of age and increase of myopic refractive error, the central corneal thickness gradually becomes thinner. There are differences in thickness among various directions, the superior direction being the thickest and the temporal inferior, the thinnest. From the center to the limbus, the thickness of the cornea gradually increases, but the values of the increase of the thickness are various in various directions, that should be paid attention to in radial keratotomy.

Characterization of ATP-sensitive potassium channel-blocking activity of ZENECA ZM181,037, a eukalemic diuretic

ZENECA ZM181,037 is a novel eukalemic diuretic from a series of 1,1-diarylcarbin-1-01-2 amines. In contrast to the standard diuretic hydrochlorothiazide, the blood pressure-lowering effect was not observed with ZENECA ZM181,037 in spontaneously hypertensive rats. ZENECA ZM181,037 demonstrated a K+ channel-blocker profile. In the isolated rat aorta stimulated with 20 mmol/l KCl, both the d- and l-enantiomer of ZENECA ZM181,037 antagonized the relaxation of cromakalim with mean pKB values of 6.4 and 6.7, respectively. In the isolated guinea-pig portal vein and urinary detrusor muscle, both enantiomers enhanced the spontaneous myogenic activity at concentrations of 1 mumol/l and higher, in addition to antagonizing the effect of cromakalim. ZENECA ZM 181,037, similar to glibenclamide, prevented a significant increase in 86Rb+ by cromakalim in both portal vein and detrusor muscle strips; however, ZENECA ZM181,037, dissimilar to glibenclamide and tolbutamide, did not increase plasma glucose when given orally to dogs. Thus, ZENECA ZM181,037 is a blocker of the ATP-sensitive K+ channel (KATP) in vascular and nonvascular tissues. In view of the profound saluresis produced by ZENECA ZM181,037, the lack of antihypertensive effect appears to result from its blocking activity on KATP in vascular tissues.

[Determination of yuanhuacine in Daphne genkwa Sieb. et Zucc. by HPLC]

Separated on phenox RP18 column with a mobile phase of methyl alcohol-water (82:18) and detected at wavelength 232nm, yuanhuacine has shown a good linearity in the range from 7.6 x 10(-3) to 0.76 microgram. The recovery is 99.56% with RSD 3.61% (n = 9). The content of yuanhuacine in Daphne genkwa is 0.00848%.

[The analgesia effect and plasma corticosterone reaction during stress in adult rats treated neonatally with monosodium glutamate]

In the present investigation, it was found that the number of beta-endorphin (beta-END)-immunoreactive neurons of hypothalamic arcuate nucleus (ARC) in MSG-treated rats decreased by 60.7%. No significant differences in the baseline pain threshold and the baseline corticosterone (CS) level were observed between the MSG-treated group and the control group. After electrical foot shock for 30 min, the analgesia effect was decreased significantly (P < 0.001) in MSG-treated rats, while the CS levels of both MSG-treated rats and control rats were increased remarked (P < 0.01). The results suggest that the beta-END neurons of ARC were involved in analgesia, but not in CS reaction during stress.

Diuretic and antihypertensive activity of ZENECA ZM224,832: a novel eukalemic diuretic with calcium channel blocking activity

ZENECA ZM224,832 is a novel eukalemic diuretic from the aminomethylphenol pyrazine series which demonstrated a profile of calcium channel blockers. It produced diuretic and saluretic effects in animals but had only minimal alterations in kaliuresis after oral administration. In contrast to standard diuretics, the plasma K+ concentration was not altered in conscious dogs treated for 14 days with ZENECA ZM224,832 and the concurrent plasma renin activity was also minimally elevated. The isolated rat aorta evaluation indicated that ZENECA ZM224,832, like tiapamil and nifedipine, inhibited vascular smooth muscle tone by inhibiting voltage-dependent calcium channels. ZENECA ZM224,832 produced a dose-dependent decrease of blood pressure in spontaneously hypertensive rats (SHR) in which the antihypertensive activity was not noted with HCTZ. In addition, ZENECA ZM224,832, similar to diltiazem, produced an acute blood pressure lowering effect in nephrectomized SHR which was independent of its diuretic activity. It is concluded that ZENECA ZM224,832 is a potent eukalemic diuretic with calcium channel blocking properties.

Maxillary osteonecrosis after radiotherapy for nasopharyngeal carcinoma

A case of extensive osteoradionecrosis of the posterior maxillae, pterygoid plates and floor of the sphenoid sinuses is reported. The patient received more than one full course of radical radiotherapy for nasopharyngeal carcinoma. Although there was complete remission of the tumour, she suffered from repeated episodes of gum bleeding which was found to be due to oroantral fistulas and severe dental decay. The large fraction dose and total dose, severe dental caries and xerostomia are the most likely contributory causes to this unusual complication in our patient.

Stereoselective blockade of amphibian epithelial sodium channels by amiloride analogs

The blockade of amphibian epithelial sodium channels by amiloride has been shown to not be a simple diffusion-limited encounter but rather a selective binding process with the rate of approach of the molecule for the channel site determined by the side chain at position 2 of the pyrazine ring and the stability of the blocking complex provided largely by the bond of the ligand at position 6. The presence of such a putative channel-associated receptor suggests that the sodium channel might have chiral recognition for its blockers. Using the short-circuit technique to measure the amiloride-sensitive sodium current through the apical membrane of the toad urinary bladder and frog skins, we evaluated the sodium channel-blocking potency of three enantiomeric pairs of amiloride analogs with chiral centers on the side chain. We demonstrated the stereoselectivity in sodium channel blockade of those analogs and confirmed the existence of a second attachment site on the channel for interacting with the lipophilic ligand on the side chain of the analog molecule to enhance its blocking activity. Depending on the separation between the chiral carbon and the pyrazine ring and the chemical groups on the chiral carbon, the eudismic ratio for the 50% inhibition constant of the enantiomers, i.e., the ratio of the sodium channel-blocking potency of the more active enantiomer to that of the less active enantiomer, was found to range from slightly more than 1 to more than 100.

Renal and antihypertensive effects of a novel eukalemic diuretic, ICI 207,828

ICI 207,828, an aminomethylphenol pyrazine derivative, produces water diuretic effects with only minimal alterations in kaliuresis in dogs and rats after oral and parenteral administration. In the dog, ICI 207,828 reached maximum activity at a dose of 10 mg/kg, p.o. This was comparable to that of hydrochlorothiazide (HCTZ) at a dose of 5 mg/kg, p.o. or higher. In the rat, a dose of 30 mg/kg, p.o. of ICI 207,828 was comparable to the maximum of water diuretic and saluretic response obtained with HCTZ at a dose of 10 mg/kg, p.o. Based upon studies using in vitro amphibian models of the mammalian nephron, ICI 207,828 appeared to act on both the thick ascending limb of the loop of Henle and the late distal nephron. In the toad bladder preparation, ICI 207,828 inhibited Na+ transport when placed on either the mucosal (amiloride-like) or serosal (thiazide-like or loop diuretic-like) sides. This compound also inhibited Cl- transport in the toad cornea preparation (loop diuretic-like). ICI 207,828 did not change plasma K+ significantly in dogs dosed for 14 days at doses having diuretic effects (5 and 10 mg/kg, p.o., daily). In contrast, HCTZ consistently decreased plasma K+, whereas amiloride increased it significantly. ICI 207,828 demonstrated antihypertensive effects in spontaneously hypertensive rats. At 30 mg/kg, p.o., b.i.d., ICI 207,828 and HCTZ produced approximately equal antihypertensive activities during a 3 1/2-day treatment period. The pharmacological profile of ICI 207,828 indicates that this compound is a potent eukalemic diuretic and antihypertensive agent in animals.

β-Adrenoceptor Subtypes in the Detrusor of Guinea-Pig Urinary Bladder

beta-Adrenoceptors have been demonstrated in the urinary bladders of many animals including the guinea pig. However, there is little information on the subtypes involved in the antispasmodic activity of beta-adrenoceptor activation in the guinea-pig detrusor. The present study uses the non-selective beta-agonist isoproterenol, the antagonist nadolol, the beta 2-selective agonists salbutamol and terbutaline, the antagonist ICI 118551, and the beta 1-selective antagonist metoprolol, to demonstrate functionally the subtypes existing in the guinea-pig detrusor. Isoproterenol dose-dependently reduces the myogenic activity in the guinea-pig detrusor induced by mild depolarization with 20 mM potassium in the tissue bath. At the supramaximal concentration of 30 microM, isoproterenol achieves 73 +/- 2% of the reference maximal response. This activity of isoproterenol is reduced to 9 +/- 5, 24 +/- 6 and 54 +/- 1% in the total blockade of beta, beta 1 and beta 2 with nadolol, metoprolol and ICI 118551, respectively. Consistently, salbutamol and terbutaline at the same concentration produce only 35 +/- 1 and 38 +/- 4% of the response, respectively. Thus, both beta 1- and beta 2-adrenoceptors are present in the detrusor of the guinea-pig urinary bladder. Although activation of either subtype results in antispasmodic action, the larger portion of the antispasmodic activity appears to be associated with the activation of the beta 1-subtype.

Comparison of the in vitro effects of K+ channel modulators on detrusor and portal vein strips from guinea pigs

The effects of K+ channel openers and blockers on smooth muscles of vascular and nonvascular origin from guinea pigs have been investigated. Cromakalim, pinacidil, nicorandil and minoxidil sulfate all abolished the spontaneous myogenic activity of the guinea pig portal vein and the KCl-evoked activity of detrusor strips with the same rank order of ptoency. Whereas both apamin and charybdotoxin stimulated myogenic activity of the detrusor strips, they produced insignificant effects on spontaneously active portal vein strips and failed to antagonize the mechanoinhibitory effects of cromakalim in the two tissues. Glibenclamide, on the other hand, only stimulated the myogenic activity of portal vein strips but antagonized the mechanoinhibitory effects of cromakalim, pinacidil, nicorandil and minoxidil sulfate in both tissues. Rubidium, at millimolar concentrations, stimulated the myogenic activity, and antagonized the actions of cromakalim in both tissues. The data indicate that there are definite functional dissimilarities as exhibited by the differential response of the two tissues to K+ channel modulators. These findings may be exploited in the design of new drugs with tissue selectivity.

[Changes in serum LDH isozymogram in burn shock]

The changes in LDH isozymogram of 36 burned patients in shock period are reported. The results show as follows: 1. The characteristics of LDH isozymogram spectrum are: A. LDH1 greater than LDH2; B. The activity of LDH5 is enhanced. C. The 3 main types of LDH isozymogram spectrum are: LDH1 greater than LDH2 greater than LDH3 greater than LDH4 greater than LDH5 LDH1 greater than LDH2 greater than LDH3 greater than LDH5 greater than LDH4 LDH1 greater than LDH2 greater than LDH5 greater than LDH3 greater than LDH4 2. In the severe and extensive cases, the incidence of LDH1 greater than LDH2 is higher.

Influence of pentobarbital and chloralose anesthesia on quinidine-induced effects on atrial refractoriness and heart rate in the dog

The effects of pentobarbital and chloralose on the atrial effective refractory period (AERP), atrial and ventricular rates, and mean blood pressure and also on the effects of quinidine on the same parameters were investigated in dogs with chronic atrioventricular block and implanted atrial pacing electrodes. Pentobarbital (30 mg/kg) increased the AERP by up to 12%, atrial and ventricular rates by 39 and 40%, respectively, and after initial lowering (48%) it increased the mean blood pressure (46%). Chloralose (100 mg/kg) increased the AERP (less than 30 min) by up to 7%, the atrial rate by 49%, the ventricular rate (less than 5 min) by 18%, and the mean blood pressure by 47%. In conscious dogs, quinidine at cumulative doses of 2, 4, and 8 mg/kg, i.e., at plasma levels between 2.7 +/- 0.6 and 6.3 +/- 1.3 micrograms/ml, increased the AERP by up to 21, 28, and 46%, the atrial rate by 49, 65, and 72%, and the ventricular rate (less than or equal to 5 min) by 17, 14, and 14%, and lowered the mean blood pressure by 19, 33, and 43%, respectively. Pentobarbital increased the quinidine-induced lengthening of the AERP by up to 10, 21, and 25 ms, respectively, and reduced the corresponding atrial (38, 53, and 67 beats/min) and ventricular (4, 4, and 5 beats/min) chronotropic effects. In contrast, chloralose reduced the quinidine-induced lengthening of the AERP (5, 12, and 22 ms, respectively), but did not modify the corresponding atrial and ventricular chronotropic effects. Neither pentobarbital nor chloralose altered quinidine plasma levels or the hypotensive effects of this drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Comutagenesis of sodium arsenite with ultraviolet radiation in Chinese hamster V79 cells

Solar ultraviolet radiation has been associated with the induction of skin cancer. Recent studies have indicated that near-ultraviolet, especially UVB, is mutagenic. Exposure to trivalent inorganic arsenic compounds has also been associated with increased skin cancer prevalence. Trivalent arsenic compounds are not mutagenic per se, but are comutagenic with a number of cancer agents. Here, we test the hypothesis that arsenite enhances skin cancer via its comutagenic action with solar ultraviolet radiation. Irradiation of Chinese hamster V79 cells with UVA (360 nm), UVB (310 nm) and UVC (254 nm) caused a fluence-dependent increase in mutations at the hprt locus. On an energy basis, UVC was the most mutagenic and UVA the least. However, when expressed as a function of toxicity, UVB was more mutagenic than UVC. Nontoxic concentrations of arsenite increased the toxicity of UVA, UVB and UVC. Arsenite acted as a comutagen at the three wavelengths; however, higher concentrations of arsenite were required to produce a significant (P less than 0.05) comutagenic response with UVB. The increased mutagenicity of UVB and UVA by arsenite may play a role in arsenite-related skin cancers.

Photodynamic therapy in the treatment of malignant tumours: an analysis of 540 cases

Malignant tumours (540 cases), including tumours of the lung, oesophagus, cardia, stomach, rectum, bladder, other urinary genital organs, face and mouth, eyes, ear, nose and throat (ENT), head and neck, breast and skin, were treated using photodynamic therapy (PDT) between 1982 and 1985 in Beijing. All of the cases were identified pathologically and the patients received haematoporphyrin derivative (HPD) (5 mg kg-1) intravenously 48-72 h prior to PDT. An argon-pumped dye laser emitting at 630 nm was used for the treatment. The results were as follows: complete response (CR) was obtained in 227 cases (42.1%), partial response (PR) was obtained in 114 cases (21.1%), mild response (MR) was obtained in 120 cases (22.2%) and 79 cases (14.6%) showed no response (NR). The effectiveness of PDT in the different organs was compared. HPD fluorescence was examined in 409 cases of malignant tumours: 344 lesions (84.1%) revealed red fluorescence (positive reaction), 32 gave an equivocal response and 33 gave a negative reaction. Positive fluorescence was seen in all types of malignant tumour in our study. Indications and limitations of PDT for the different organs are discussed and compared.

Separation and characterization of the metabolic products of lappaconitine in rat urine by high-performance liquid chromatography

The separation and characterization of the metabolic products of lappaconitine in rat urine by high-performance liquid chromatography with electrochemical and ultraviolet detection are described. Urine samples from rats intravenously administered lappaconitine hydrobromide were extracted with chloroform and then purified on a Sep-Pak C18 cartridge. The subsequent resolution into individual compounds was achieved by high-performance liquid chromatography. Identification of these compounds was based on comparisons of the chromatographic behaviour and the detector response with those of authentic samples. Changes in the ratio of lappaconitine to its metabolites in rat urine with time after dosing led to a proposal for one of the probable metabolic pathways of lappaconitine in the rat.

Studies on the metabolism of lappaconitine in humans. Identification of the metabolites of lappaconitine in human urine by high performance liquid chromatography

The metabolites of lappaconitine in the urine of humans having been previously administered intramuscularly with lappaconitine hydrobromide were studied using high performance liquid chromatography with electrochemical and ultraviolet detection. The urine was extracted by means of liquid- and solid-phase extractions. Each of the metabolites of lappaconitine was purified by high performance liquid chromatography on a reversed phase column and identified on the basis of the chromatographic behaviour and the detector response. It was proved that lappaconitine, N-deacetyl-16-O-demethyllappaconitine and N-deacetyllappaconitine were excreted in urine from humans receiving lappaconitine.

[Changes in metallothionein content of the heart and liver during acute myocardial infarction in rats]

Metallothionein (MT) is an important endogenous anti-injury substance involved in the defensive system. In myocardial infarction model produced by left coronary artery occlusion in-rat, the content of left ventricular myocardial MT was significantly increased to a maximum on 4th day by 6-fold compared with preoperative value, and the content of hepatic MT increased by 3.5-fold on the 2nd day. During the whole experimental period (seven days) the MT content in heart and liver was significantly higher than those in the pre-operation period (P less than 0.01). Pretreatment with reserpine did not alter the dynamic changes of cardiac and liver MT content during myocardial infarction. The above results suggest that this increase in tissue MT is not influenced by catecholamine.

Mechanism of comutagenesis of sodium arsenite with n-methyl-n-nitrosourea

Arsenic compounds are known carcinogens. Although many carcinogens are also mutagens, we have previously shown that sodium arsenite is not mutagenic at either the Na+/K+ ATPase or hprt locus in Chinese hamster V79 cells. It can, however, enhance UV-mutagenesis. We now confirm the nonmutagenicity of sodium arsenite in line G12, a pSV2gpt-transformed V79 (hprt-) cell line, which is able to detect multilocus deletions in addition to point mutations and small deletions. The lack of arsenic mutagenicity has led to studies emphasizing its comutagenicity. Sodium arsenite at relatively nontoxic concentrations (5 microM for 24 h or 10 microM for 3 h) is comutagenic with N-methyl-N-nitrosourea (MMU) at the hprt locus in V79 cells. Using a nick translation assay, which measures DNA strand breaks by incorporating radioactive deoxyribonucleoside monophosphate at their 3'OH ends in permeabilized cells, we found that much more incorporation was seen in cells treated with MNU (4 mM, 15 min) followed by 3-h incubation with 10 microM sodium arsenite compared with cells exposed to the same MNU treatment followed by 3-h incubation without sodium arsenite. This result shows that in the presence of arsenite, strand breaks resulting from MNU or its repair accumulate over a 3-h period. We suggest that the repair of MNU-induced DNA lesions may be inhibited by arsenite either by affecting the incorporation of dNMPs into the MNU-damaged DNA template or by interfering with the ligation step.

[Nd-YAG laser treatment of tracheobronchial lesions]

From January 1987 to May 1988, 32 cases with tracheobronchial lesions were treated with Nd-YAG laser. Complete restoration of the airway was achieved in one case of leiomyoma, adenoma, carcinoid and mucous epithelioma each, 2 cases of polyp and 7 cases of granuloma. Significant restoration was seen in one case of granuloma, 2 cases of hematoma and papilloma, each, 3 cases of amyloidosis and partial restoration in one case of granuloma. The remaining 10 cases with squamous cell carcinoma and adenocarcinoma with severe airway obstruction were treated by Nd-YAG laser for palliative purpose only. Four of them revealed significant remission and 6 responded with partial remission. No severe complication was observed during or after the procedures. Nd-YAG laser treatment provides a new curative method avoiding resection of the lung in benign lesions and a palliative therapy for unresectable obstructive malignant tumors.

Genetic toxicology of lead compounds

We have investigated the activity of insoluble and soluble lead compounds in inducing mutagenesis, cell transformation and sister chromatid exchange in mammalian cells. Insoluble lead sulfide, readily phagocytized, was more than four times as toxic to V79 cells on a microM basis, than two moderately soluble lead compounds although the exposure time for the soluble salts was five times longer. These findings demonstrate the importance of different cellular mechanism(s) of metal uptake and bioavailability. Both insoluble lead sulfide and more soluble lead nitrate were mutagenic at the HPRT locus in V79 cells. Although less mutagenic at the higher concentrations, lead nitrate at a concentration of 500 microM enhanced the mutation frequency greater than 6-fold above background following a 5-day exposure. Although the mechanism(s) by which lead induces mutations is unknown, failure of both compounds to induce SCE and DNA single-strand breaks, detectable by alkaline elution, suggests that lead-induced mutations may not be a result of direct damage to DNA but may occur via indirect mechanisms including disturbances in enzyme functions important in DNA synthesis and/or repair, or in DNA-helical structure. Lead acetate also transformed SHE cells in a dose-response fashion following a 48-h exposure. Our results indicate that lead compounds may be genotoxic by an indirect mechanism, and lend support to the view that lead is a carcinogen.

Bumetanide stimulation of sodium permeability of the apical membrane of toad urinary bladder

The effects of bumetanide on Na transport in the isolated toad urinary bladder were investigated. When applied to the serosal side, this loop diuretic inhibited Na transport. By contrast, when applied to the mucosal side, it stimulated Na transport by increasing the apical Na permeability. These dual effects of bumetanide were also observed with the loop diuretic furosemide. The mucosal action of bumetanide was attributable to release of Na self-inhibition, as evidenced by its dependency on mucosal Na concentration and its interaction with another apical Na permeability stimulator, p-chloromercuriphenyl sulfonate. The stimulatory action of bumetanide was not reduced by the natriferic effect of antidiuretic hormone, but it was totally blockable by the epithelial Na channel blocker amiloride. Bumetanide, however, caused a leftward shift of the concentration-response curve of amiloride on Na current as predicted from its effect on Na self-inhibition. This stimulatory activity of bumetanide and furosemide as demonstrated in the in vitro isolated amphibian epithelia suggests that these loop diuretics also have the potential to stimulate Na transport at the distal portion of the mammalian nephron. Thus, this property of these diuretics might be one of the factors contributing to the observation of increased Na reabsorption along the distal tubule after in vivo administration of furosemide and piretanide as reported in some micropuncture studies.

Amphibian cornea as a model for studying intrinsic activities of loop diuretics

The inhibitory activity of various standard diuretics and compounds on Cl- transport in the toad cornea has been investigated. The relative potency of these diuretics shows a pattern and follows a sequence similar to their inhibitory potency on salt reabsorption in the isolated mammalian cortical thick ascending limb of Henle's loop. The suitability and convenience of using toad cornea as an in vitro model for that segment of the mammalian nephron is well demonstrated.

ICI 147,798: a novel diuretic agent with beta adrenoceptor blocking activity

ICI 147,798 is a novel compound which has both diuretic and beta adrenoceptor blocking properties in a single molecule. The natriuretic activity at 30 mg/kg p.o. was about 65% of the hydrochlorothiazide value at 10 mg/kg p.o. in saline-loaded rats; the corresponding kaliuretic activity was 42%. The natriuretic and the kaliuretic activity of ICI 147,798 in dogs were similar to that of hydrochlorothiazide over the doses 1 to 20 mg/kg p.o., although significantly less kaliuresis was obtained with ICI 147,798 at 1 mg/kg p.o. In the toad bladder preparation (analogous to the distal mammalian nephron), ICI 147,798 inhibited Na+ transport with mucosal and serosal IC50 values of 56 and 120 microM, respectively. ICI 147,798 inhibited isoproterenol-induced tachycardia in rats, cats, guinea pigs and dogs; these effects were associated with antagonism of isoproterenol vasodepressor responses. The pKB values of ICI 147,798 were 9.1 and 8.8 in isolated right atria and trachea of guinea pigs, respectively. ICI 147,798 did not exhibit local anesthetic activity in rabbit cornea and intrinsic sympathomimetic activity in catecholamine-depleted dogs and rats. Duration of beta blockade after a p.o. dose of 1 mg/kg in dogs followed the sequence: nadolol greater than ICI 147,798 greater than atenolol greater than timolol greater than propranolol. It is concluded that ICI 147,798 is a novel diuretic agent with nonselective beta blockade, and it appears to have the potential of a direct tubular action.

Structure-activity relationship of amiloride analogs as blockers of epithelial Na channels: II. Side-chain modifications

The overall on- and off-rate constants for blockage of epithelial Na channels by amiloride analogs were estimated by noise analysis of the stationary Na current traversing frog skin epithelium. The (2-position) side chain structure of amiloride was varied in order to obtain structure/rate constant relationships. Hydrophobic chain elongations (benzamil and related compounds of high blocking potency) increase the stability of the blocking complex (lowered off-rate), explained by attachment of the added phenyl moiety to a hydrophobic area near the site of side chain interaction with the channel protein. Some other chain modifications show that the on-rate, which is smaller than a diffusion-limited rate, varies with side chain structure. In several cases this effect is not attributable to steric hindrance on encounter, and implies that the side chain interacts briefly with the channel protein (encounter complex) before the main blocking position of the molecule is attained. The encounter complex must be labile since the overall rate constants of blockage are not concentration-dependent. In two cases, changes at the 2-position side chain and at other ring ligands, with known effects on the blocking rate constants, could be combined in one analog. The rate constants of blocking by the resulting compounds indicate that the structural changes have additive effects in terms of activation energies. Along with other observations (voltage dependence of the rate constants and competition with the transported Na ion), these results suggest a blocking process of at least two steps. It appears that initially the 2-position side chain invades the outward-facing channel entrance, establishing a labile complex. Then the molecule is either released completely (no block) or the 6-ligand of the pyrazine ring gains access to its receptor counterpart, thus establishing the blocking complex, the lifetime of which is strongly determined by the electronegativity of the 6-ligand.

Chronotropic cardiac effects of histamine in the conscious dog with chronic atrioventricular block: interactions with the autonomic nervous system

Chronotropic effects of histamine and dimaprit were studied in the conscious dog with chronic atrioventricular block. Histamine at 0.2-5 micrograms/kg and dimaprit at equimolar doses (i.e. 0.25-6.25 micrograms/kg) increased atrial rate dose-relatedly. Blockade of muscarinic receptors reduced these effects and simultaneous blockade of muscarinic and beta-adrenergic receptors abolished them. Histamine and dimaprit moderately increased ventricular rate. Blockade of muscarinic receptors did not modify these effects, but blockade of beta-adrenoceptors with or without simultaneous blockade of muscarinic receptors suppressed them. After blockade of beta-adrenoceptors, histamine and more rarely dimaprit sometimes decreased atrial and ventricular rates. These effects were prevented by additional muscarinic blockade. Histamine and dimaprit lowered mean blood pressure to the same degree before and after each antagonist. The positive chronotropic effects of histamine and dimaprit, at these doses, are probably reflex responses to their hypotensive effects. The negative chronotropic effects of histamine after pindolol are due to muscarinic receptor activation. No evidence was found to implicate histamine-specific receptors in any of the chronotropic effects of histamine and dimaprit.

Propafenone in the conscious dog with chronic atrioventricular block: mechanisms of chronotropic cardiac effects and plasma concentration-response relationships

The chronotropic effects of propafenone were studied in the conscious dog with chronic atrioventricular block. Propafenone at 0.5-4 mg/kg, i.e., at plasma levels within the assumed therapeutic range, dose relatedly raises atrial rate. This effect falls off and bradycardia is even observed at 0.5 and 1 mg/kg once plasma levels have dropped below 330 +/- 31 ng/ml. After atropine, propafenone (2 mg/kg) lowers atrial rate, after propranolol it raises it, and after pindolol it does not modify it. Propafenone dose relatedly raises ventricular rate, although again this effect subsequently reverses at 4 mg/kg. After atropine, propranolol, and pindolol, propafenone (2 mg/kg) instead of initially raising ventricular rate lowers it lastingly. It initially lowers mean blood pressure according to dose. At 2 mg/kg neither this effect nor the plasma levels are modified by the antagonists. The beta-blocking potency is 1/40th that of propranolol as determined against isoproterenol-induced cardioacceleration. These results show that the atrial cardioacceleration due to propafenone results from direct and reflex vagolytic action and that the bradycardia at low plasma levels (buffered by the vagolytic effect at high levels) seems due to its membrane-stabilizing action. They also show that the initial ventricular cardioacceleration is a reflex response to its hypotensive effect, whereas the ventricular bradycardia at high doses is attributable to its membrane-stabilizing action and its albeit weak beta-blocking action.

Effects of detergents on sodium transport in toad urinary bladder

The effects of ionic, nonionic and zwitterionic detergents (zwittergents) on apical sodium permeability of toad urinary bladder were investigated. Applied to the mucosal side at concentrations less than 1/100 of their respective critical micellar concentration (CMC), sodium lauryl sulfate, Triton X-100 and a series of sulfobetaine zwittergents reversibly increased amiloride-sensitive sodium current. These detergents decreased the current at concentrations higher than 1/100 of the CMC and caused large, irreversible increases of tissue electrical conductance at a concentration close to the CMC. Nonionic detergent Tween 80, however, stimulated the current at concentrations from 1/100 to 10,000 of its CMC. The maximum stimulation of current by each zwittergent occurred at 1/100 of its CMC, and the larger the CMC, the greater the stimulation attainable. Analysis of the dependence of current on mucosal sodium concentration in the presence of stimulating doses of a zwittergent and Tween 80 showed that the increase in current was not the result of increased apical maximum sodium permeability, but the consequence of removal of sodium self-inhibition. The amiloride dose-response curve in the presence of stimulating dose of zwittergent was shown to shift to the left and yield a smaller apparent inhibition constant as predicted on the basis of such a removal and an unaltered intrinsic amiloride blocking kinetic.

Phorbol myristate acetate inhibits anti-IgM-mediated signaling in resting B cells

Cross-linking the membrane immunoglobulins of resting B cells leads to activation as judged by increased inositol phospholipid metabolism, intracellular free calcium concentration ([Ca2+]i), and cell volume. Such activated B cells enter S phase in the presence of B-cell stimulatory factor 1. Phorbol myristate acetate (PMA) is a potent inhibitor of anti-IgM- and anti-IgD-stimulated B-cell responses. In B cells concentrations of PMA ranging from 0.1 to 100 ng/ml completely inhibit anti-IgM-stimulated DNA synthesis and block anti-IgM-stimulated increases in inositol phospholipid metabolism and in [Ca2+]i. Preincubation periods as short as 4 min block these effects although longer preincubations are somewhat more effective in inhibiting increases in [Ca2+]i. Preincubation with PMA for 1.5 hr does not diminish expression of membrane IgM. This strongly suggests that PMA inhibits responses of resting B cells to anti-IgM by interrupting signal transmission rather than by diminishing cross-linking of membrane immunoglobulin on B cells. In contrast to resting B cells, B cells activated in vitro for 29 hr show enhanced responses to anti-IgM in the presence of PMA.