Candesartan Treatment for Peripheral Occlusive Arterial Disease after Stent Angioplasty

OBJECTIVES

In this prospective, double-blind, placebo-controlled study we observed the influence of treatment with candesartan 8mg on restenosis rates after stent implantation into the femoral artery 6 months after percutaneous transluminal angioplasty (PTA). We hypothesised that angiotensin II type 1 (AT1)-receptor blockade with candesartan would reduce restenosis rates by reducing angiotensin II-mediated intima hyperproliferation within the stented vessel segment in patients with peripheral occlusive disease.

PATIENTS AND METHODS

Eighty-seven patients with peripheral occlusive arterial disease stage IIb who had been successfully treated with PTA and stent implantation were randomised to receive orally either candesartan 8mg (n = 44) or placebo (n = 43). Follow-up included evaluation of the degree of stenosis and thickness of the intima-media complex (primary endpoint). In addition, thickness of the interventricular septum, crurobrachial pressure ratios, and pain-free walking distance were determined (secondary endpoints).

RESULTS

The degree of stenosis after 6 months was not significantly different between the groups studied (35.9 +/- 39.6% for candesartan vs 36.0 +/- 38.4% for placebo). Relevant restenosis including stent occlusions was found in nine patients (20.5%) in the candesartan group and in ten patients (23.3%) in the placebo group. The thickness of the intima-media complex 6 months after stent implantation was 1.60 +/- 0.32mm in the candesartan group and 1.64 +/- 0.32mm in the placebo group (not significant). There were no differences in secondary endpoints between the treatment groups. Controls after 3 months (20.9 +/- 33.6% for candesartan vs 27.6 +/- 38.3% for placebo; p = 0.39) and 9 months (44.1 +/- 40.8% for candesartan vs 47.7 +/- 37.2% for placebo; p = 0.67) of therapy revealed a lower degree of stenosis in patients treated with candesartan.

CONCLUSIONS

Although not significant, candesartan treatment tended to improve the prognostic benefits after stent implantation, suggesting that an antiproliferative effect after stenting may need higher doses than an antihypertensive effect of the drug. This hypothesis requires confirmation in further prospective studies with higher daily doses of candesartan, which are already in progress.

Expression of hair keratins in the adult nail unit: an immunohistochemical analysis of the onychogenesis in the proximal nail fold, matrix and nail bed

BACKGROUND

Recently, the expression profiles of the members of the complex hair keratin family have been determined in the human anagen hair follicle. In contrast, the details of hair keratin expression in the human nail unit are poorly known.

OBJECTIVES

In order to fill this gap, we have performed an immunohistochemical study of the adult human nail unit by means of specific antibodies against nine hair keratins of both types (hHa2, hHb2, hHa5, hHb5, hHa1, hHb1, hHb6, hHa4 and hHa8) as well as three epithelial keratins (K5, K17 and K10).

METHODS

Formalin-fixed paraffin sections of adult nails were examined using monoclonal and polyclonal keratin antibodies, respectively. Longitudinal as well as transverse sections were investigated.

RESULTS

Our study revealed two types of epithelial tissue compartments in the nail unit. The first comprised the eponychium and hyponychium and the nail bed, which expressed only epithelial keratins. While keratins K5, K17 (basal) and K10 (suprabasal) were found in the orthokeratinizing eponychium and hyponychium, throughout, the nail bed epithelium expressed only K5 and K17. The second type comprised the apical and ventral matrix which exhibited a mixed pattern of epithelial and hair keratin expression. Thus, K5 and K17 were expressed in the entire multilayered basal cell compartment of the apical and ventral matrix; however, in the latter, K5 and K17 also occurred in the lowermost layers of the overlying keratogenous zone. The hair matrix keratin hHb5, but not its type II partner hHa5, was seen in the entire keratogenous zone of the apical and ventral matrix, but was also located in the uppermost cell layers of the basal compartment of the ventral matrix, where it overlapped with K5 and K17. Similar to their sequential expression in the hair follicle cortex, hair keratins hHa1, hHb1, hHb6 and hHa4 were consecutively expressed in the keratogenous zone of both the ventral and, albeit less distinctly, apical matrix, with hHa1 initiating in the lowermost cell layers. The expression of hHa8 in only single cortex cells of the hair follicle was also preserved in cells of the keratogenous zone. In the region of the so-called dorsal matrix, we observed two histologically and histochemically distinct types of epithelia: (i) a dominant type, histologically similar to the eponychium and an associated K5, K17 and K10 keratin pattern which clearly extended into the apical matrix, and (ii) a minor type, histologically resembling the postulated dorsal matrix without a granular layer and a cuticle, and exhibiting extended K5 expression as well as hair keratin expression in superficial cells.

CONCLUSIONS

The coexpression of hHb5 with K5 and K17 in the uppermost cell layers of the basal compartment and the lowermost layers of the keratogenous zone of the ventral matrix prompts us to designate this region the prekeratogenous zone of the ventral matrix. The two alternating types of histology and keratin expression in the dorsal matrix identify this region as a transitional zone between the eponychium and the apical matrix. Finally, our data clearly show that the ventral matrix is the main source of the nail plate. In addition, the mixed scenario of hair and epithelial keratins, including demonstrable amounts of K10, in superficial cells of the apical matrix, lends support to the notion that the dorsal portion of the nail is generated by the apical matrix.

Hair keratin pattern in human hair follicles grown in vitro

The keratin family includes epithelial (soft) keratins and hair (hard) keratins, and can be divided into acidic type I and basic to neutral type II subfamilies. Recently, nine type I and six type II hair keratin genes have been characterized through the screening of a human PAC library. The expression of these genes in the hair follicle was determined in vivo and a combined catalog of acidic and basic hair keratins was established. In this study, we investigated the expression and localization of most of the human hair keratin members of both types in human hair grown in vitro. We show that in vitro growth of hair follicles for 10 days in complete William's E culture medium did not alter the expression pattern of hair keratins. Similarly to the in vivo situation, each hair keratin was localized in precise and discrete compartments of the follicle, ranging from the matrix to the upper cortex and/or the hair cuticle. This study shows that the increase in length of in vitro grown follicles was accompanied by the proper hair shaft keratinization process. It also shows that hair follicle integrity was maintained in vitro, both in terms of gross morphology and molecular organization despite the complexity of the keratin expression pattern.

Use of abciximab and tirofiban in patients with peripheral arterial occlusive disease and arterial thrombosis

Acute peripheral arterial occlusive disease is an important factor affecting the mobility and mortality rate of elderly patients. Catheter-guided arterial thrombolysis in these patients has its limitations: long lysis times, early occlusions, and high restenosis rates. The study investigated whether the use of tirofiban has the same favorable effect as the glycoprotein (GP) IIb/IIIa receptor antagonist abciximab and whether lysis times can be shortened and the disease course positively influenced by these substances. Sixty patients were randomly assigned to 2 groups. Each group received 5 mg recombinant tissue-type (rt-PA) plasminogen activator by slow intra-arterial injection for 10 minutes followed by 5 mg rt-PA per hour and 500 IU heparin per hour IV. After randomization 1 group received a bolus of 0.25 mg abciximab per kg body weight followed by 10 mg per minute IV for 12 hours (heparin was reduced to 250 IU/hr). The other group received a bolus of 0.4 microg tirofiban per kg body weight as well as postinterventional medication with 0.1 microg tirofiban per minute and kg body weight for 24 hours. During medication with GP IIb/IIIa inhibitor, the patients received a reduced heparin dosage for 24 hours. After 24 hours both groups received 200 mg aspirin orally and full heparinization controlled on the basis of the partial thromboplastin time. The following efficacy criteria were analyzed: rehospitalization events, reintervention events, and amputations within 6 months. Secondary endpoints were changes in the Fontaine stage, the crurobrachial index, the distance to claudication, and the duration of local arterial lysis. No significant differences were found between the abciximab and tirofiban groups in terms of the rehospitalization, reintervention, or amputation rates, nor were there any group differences in the total number of events. The secondary parameters, such as the crurobrachial index, distance to claudication, and Fontaine stage, also showed no significant differences between the 2 groups within 6 months. The duration of lysis was significantly shorter in the abciximab group. Major bleeding events did not occur in either group. With regard to the adverse effect rate, there were no significant differences between the 2 groups. Both abciximab and tirofiban can be used successfully in patients with peripheral arterial occlusive disease and arterial thrombosis.

Fracture toughness of snow in shear under friction

The fracture toughness of snow in shear is one of the most relevant parameters when studying the mechanics of snow slab avalanche release. Double-cantilever snow beams were loaded asymmetrically to determine K(IIc). If crack surfaces touch under applied pressure, the fracture toughness in shear of snow (rho=247 kg m(-3)) is K(IIc)=680+/-60 Pa m(1/2). Screening of the stress intensity at the crack tip occurs by Newtonian friction with k=1.3+/-0.47 along the crack faces.

Potential use of a low-molecular-weight heparin to prevent restenosis in patients with extensive wall damage following peripheral angioplasty

The long-term outcome of primary successful percutaneous transluminal angioplasty (PTA) for patients with peripheral occlusive arterial disease (POAD) is frequently compromised by the development of restenosis, especially when extensive dissections result from the angioplastic procedure. Unfortunately, prevention of the occlusive process by means of drugs such as antithrombotics, anticoagulants, thrombolytics, corticosteroids, lipid reducers, or cytostatics has not been demonstrated convincingly. The authors sought to clarify whether such patients could benefit from the postsurgical administration of low-molecular-weight heparin. A total of 172 POAD patients with extensive dissections after PTA in the pelvic or upper leg regions were randomized for 7-day post-PTA intravenous treatment with either full heparinization or nadroparin calcium followed by adjunctive oral aspirin for 6 months. The primary outcome measure was the degree of stenosis (normal findings; stenosis < 50%, > 50%, > 80%, occlusion) before and after angioplasty, as well as 3 weeks and 3 and 6 months after dilation; secondary efficacy criteria included changes in the Fontaine stage and in the crurobrachial ratio. No significant treatment-related differences were found at the 3 post-PTA follow-up examinations with regard to the degree of stenosis. This was also the case for the subgroup of patients (n = 62) who had undergone angioplasty in the pelvic region. By contrast, when angioplasty was performed in the superficial femoral artery (n = 110), the degree of restenosis was significantly lower (p<0.01) among patients receiving nadroparin calcium compared to those given heparin at week 3, month 3, and month 6. No intergroup differences emerged for secondary outcome measures in the long term or for safety parameters. These preliminary results indicate that patients with extensive dissections after PTA treatment for POAD in the upper leg region might benefit from a reduction in the rate of restenosis by administration of 7-day weight-adjusted nadroparin calcium.

The catalog of human hair keratins. II. Expression of the six type II members in the hair follicle and the combined catalog of human type I and II keratins

The human type II hair keratin subfamily consists of six individual members and can be divided into two groups. The group A members hHb1, hHb3, and hHb6 are structurally related, whereas group C members hHb2, hHb4, and hHb5 are rather distinct. Specific antisera against the individual hair keratins were used to establish the two-dimensional catalog of human type II hair keratins. In this catalog, hHb5 showed up as a series of isoelectric variants, well separated from a lower, more acidic, and complex protein streak containing isoelectric variants of hair keratins hHb1, hHb2, hHb3, and hHb6. Both in situ hybridization and immunohistochemistry on anagen hair follicles showed that hHb5 and hHb2 defined early stages of hair differentiation in the matrix (hHb5) and cuticle (hHb5 and hHb2), respectively. Although cuticular differentiation proceeded without the expression of further type II hair keratins, cortex cells simultaneously expressed hHb1, hHb3, and hHb6 at an advanced stage of differentiation. In contrast, hHb4, which is undetectable in hair follicle extracts and sections, could be identified as the largest and most alkaline member of this subfamily in cytoskeletal extracts of dorsal tongue. This hair keratin was localized in the posterior compartment of the tongue filiform papillae. Comparative analysis of type II with the previously published type I hair keratin expression profiles suggested specific, but more likely, random keratin-pairing principles during trichocyte differentiation. Finally, by combining the previously published type I hair keratin catalog with the type II hair keratin catalog and integrating both into the existing catalog of human epithelial keratins, we present a two-dimensional compilation of the presently known human keratins.

Comparison of angiotensin II receptor antagonists

Nonpeptide orally active angiotensin II type 1 (AT1) receptor antagonists are the most specific means presently available to block the renin-angiotensin enzymatic cascade. Six of these drugs have already been licensed in Europe and in the United States for the treatment of high blood pressure, and additional candidates are in the pipeline. The World Health Organisation has also recently endorsed their use for this condition. Inasmuch as AT1 receptor antagonists have proven themselves the equals of angiotensin converting enzyme inhibitors with respect to antihypertensive efficacy, but demonstrated better safety profiles, this class of drugs may be considered to be a qualitative improvement in the treatment of essential hypertension. Interestingly, the six agents now on the market diverge considerably with respect to their pharmacokinetic and pharmacodynamic properties, although it is not certain whether such differences are clinically relevant. A considerable number of large, multicentre trials are in progress to ascertain the possible longer-term organoprotective effects of these substances on cardiovascular morbidity and mortality. Because of their noteworthy safety record to date, and simple once-a-day dosage regimen, AT1 receptor antagonists have the potential to improve compliance in patients with chronic hypertension.

Expression of type I hair keratins in follicular tumours

BACKGROUND

Hair keratins are specifically expressed in hair and nails. We previously demonstrated the expression of hair keratin basic 1 mRNA in pilomatrixomas. We recently developed a method for immunohistochemical staining of the group of acidic keratins, which have not yet been investigated in human tumours.

OBJECTIVES

To study the expression of eight members of the type I hair keratin subfamily in pilomatrixomas and other skin tumours of follicular origin.

METHODS

We performed immunohistochemistry on paraffin sections of formalin-fixed pilomatrixomas (40), trichoepitheliomas (10), trichoblastomas (10), desmoplastic trichoepitheliomas (10) and basal cell carcinomas (10), using antibodies against type I hair keratins hHa1, hHa2, hHa3-II, hHa4, hHa5, hHa6, hHa7 and hHa8 as well as cytokeratin CK17.

RESULTS

While CK17 was found in almost all tumours investigated, hair keratins were exclusively expressed in pilomatrixomas. Their expression was restricted to areas of transitional cells, located between outer basophilic matricial cells and an inner zone of eosinophilic shadow cells. The most frequently and most strongly expressed hair keratins were hHa1, hHa2, hHa5 and hHa8, whereas hHa4 and hHa6 were only weakly expressed. No positive staining was observed with anti-hHa3-II and anti-hHa7 antibodies. Hair keratin expression in intermediate maturation stage pilomatrixomas resembled that of normal hair follicles, with early matricial and cuticular keratins hHa5 and hHa2 being expressed in lower transitional cells, followed by expression of early cortex keratins hHa1 and hHa8 in intermediate transitional cells and the late cortex keratins hHa4 and hHa6 in upper transitional cells. The latter were, however, seen only in a few intermediate maturation stage pilomatrixomas and were generally absent in late-stage pilomatrixomas.

CONCLUSIONS

These changes in hair keratin expression patterns indicate that the maturation of pilomatrixomas towards large areas of shadow cells is associated with a gradual loss of differentiation-specific hair keratins. The complex hair keratin expression in pilomatrixomas is a further argument in favour of a hair matrix origin of this tumour.

Characterization of a cluster of human high/ultrahigh sulfur keratin-associated protein genes embedded in the type I keratin gene domain on chromosome 17q12-21

Low stringency screening of a human P1 artificial chromosome library using a human hair keratin-associated protein (hKAP1.1A) gene probe resulted in the isolation of six P1 artificial chromosome clones. End sequencing and EMBO/GenBank(TM) data base analysis showed these clones to be contained in four previously sequenced human bacterial artificial chromosome clones present on chromosome 17q12-21 and arrayed into two large contigs of 290 and 225 kilobase pairs (kb) in size. A fifth, partially sequenced human bacterial artificial chromosome clone data base sequence overlapped and closed both of these contigs. One end of this 600-kb cluster harbored six gene loci for previously described human type I hair keratin genes. The other end of this cluster contained the human type I cytokeratin K20 and K12 gene loci. The center of the cluster, starting 35 kb downstream of the hHa3-I hair keratin gene, contained 37 genes for high/ultrahigh sulfur hair keratin-associated proteins (KAPs), which could be divided into a total of 7 KAP multigene families based on amino acid homology comparisons with previously identified sheep, mouse, and rabbit KAPs. To date, 26 human KAP cDNA clones have been isolated through screening of an arrayed human scalp cDNA library by means of specific 3'-noncoding region polymerase chain reaction probes derived from the identified KAP gene sequences. This screening also yielded four additional cDNA sequences whose genes were not present on this gene cluster but belonged to specific KAP gene families present on this contig. Hair follicle in situ hybridization data for single members of five different KAP multigene families all showed localization of the respective mRNAs to the upper cortex of the hair shaft.

A novel type II cytokeratin, mK6irs, is expressed in the Huxley and Henle layers of the mouse inner root sheath

Hair follicle differentiation involves the expression of both epithelial-type keratins or cytokeratins and hair keratins as well as hair keratin-associated proteins. In this study, a cDNA clone encoding a cytokeratin family member was isolated using RNA differential display techniques. The predicted amino acid sequence derived from this clone, revealed a homology with a number of cytokeratins, not only in the central alpha-helical regions but also in the conserved portions of the amino and carboxy terminal domains, indicating that this protein represents a new member of the mouse type II cytokeratin family. Northern blot analysis showed expression in mouse skin, but not in other tissues, including tongue, esophagus, and forestomach. One- and two-dimensional western blot analysis showed that this new cytokeratin was 57 kDa in size and ran slightly below the area of cytokeratin 5, which corresponded to that of the cytokeratin 6 family members. Both RNA in situ hybridization and immunohistochemical studies of mouse anagen hair follicles demonstrated expression of this cytokeratin in the inner root sheath hair cone during anagen III and in the Henle and Huxley layers of the inner root sheath during anagen VI. The expression of the new cytokeratin began in the hair bulb and progressed up to the height of the keratogenous zone. Taken together the sum of the data analyzed, we have termed this novel cytokeratin mK6irs (mouse gene nomenclature k2-6g) to indicate both its similar mobility with K6 in two-dimensional gels and its specific expression in the inner root sheath of the hair follicle.

Human type I hair keratin pseudogene phihHaA has functional orthologs in the chimpanzee and gorilla: evidence for recent inactivation of the human gene after the Pan-Homo divergence

In addition to nine functional genes, the human type I hair keratin gene cluster contains a pseudogene, phihHaA (KRTHAP1), which is thought to have been inactivated by a single base-pair substitution that introduced a premature TGA termination codon into exon 4. Large-scale genotyping of human, chimpanzee, and gorilla DNAs revealed the homozygous presence of the phihHaA nonsense mutation in humans of different ethnic backgrounds, but its absence in the functional orthologous chimpanzee (cHaA) and gorilla (gHaA) genes. Expression analyses of the encoded cHaA and gHaA hair keratins served to highlight dramatic differences between the hair keratin phenotypes of contemporary humans and the great apes. The relative numbers of synonymous and non-synonymous substitutions in the phihHaA and cHaA genes, as inferred by using the gHaA gene as an outgroup, suggest that the human hHaA gene was inactivated only recently, viz., less than 240,000 years ago. This implies that the hair keratin phenotype of hominids prior to this date, and after the Pan-Homo divergence some 5.5 million years ago, could have been identical to that of the great apes. In addition, the homozygous presence of the phihHaA exon 4 nonsense mutation in some of the earliest branching lineages among extant human populations lends strong support to the "single African origin" hypothesis of modern humans.

Small evolutionarily conserved RNA, resembling C/D box small nucleolar RNA, is transcribed from PWCR1, a novel imprinted gene in the Prader-Willi deletion region, which Is highly expressed in brain

Prader-Willi syndrome is a complex neurodevelopmental disorder caused by the inactivation or deletion of imprinted, paternally expressed genes in chromosome band 15q11.2. We report the identification and characterization of PWCR1, a novel imprinted gene within that region, and its mouse orthologue, Pwcr1, which was mapped to the conserved syntenic region on mouse chromosome 7. Expressed only from the paternal allele, both genes require the imprinting-center regulatory element for expression and are transcribed from the same strand. They are intronless and do not appear to encode a protein product. High human/mouse sequence similarity (87% identity) is limited to a 99-bp region called "HMCR" (for "human-mouse conserved region"). The HMCR sequence has features of a C/D box small nucleolar RNA (snoRNA) and is represented in an abundant small transcript in both species. Located in nucleoli, snoRNAs serve as methylation guidance RNAs in the modification of ribosomal RNA and other small nuclear RNAs. In addition to the nonpolyadenylated small RNAs, larger polyadenylated PWCR1 transcripts are found in most human tissues, whereas expression of any Pwcr1 RNAs is limited to mouse brain. Genomic sequence analysis reveals the presence of multiple copies of PWCR1 and Pwcr1 that are organized within local tandem-repeat clusters. On a multispecies Southern blot, hybridization to an HMCR probe encoding the putative snoRNA is limited to mammals.

Short- and long-term results of abciximab versus aspirin in conjunction with thrombolysis for patients with peripheral occlusive arterial disease and arterial thrombosis

Acute peripheral occlusive arterial disease is an important cause of morbidity and mortality, particularly among older persons. Catheter-directed thrombolytic therapy is the treatment of choice but has limitations: long lytic times, occlusions refractory to thrombolysis, and a high rate of restenosis. We conducted a pilot study to evaluate the use of the platelet GP IIb/IIIa receptor antagonist abciximab versus aspirin in conjunction with thrombolysis in patients with acute peripheral occlusive arterial disease associated with arterial thrombosis. A total of 84 patients were randomized into two equal groups to receive 5 mg recombinant tissue plasminogen activator intravenously and 500 IU heparin/hour along with either 500 mg acetylsalicylic acid or a bolus of 0.25 mg/kg abciximab followed by 10 microg/min abciximab over 12 hours (heparin reduced to 250 IU/hour). Primary efficacy criteria included the number of rehospitalizations, reinterventions, and amputations during the following 6 months. Secondary endpoints were the changes in the Fontaine stage, Bollinger index (vessel occlusion), ankle-to-brachial ratios, distance to claudication after 6 months, and the duration of the initial local lysis treatment. Adjunctive use of abciximab reduced the rates of rehospitalization, reinterventions, and amputations versus results with the use of aspirin (10 vs 14 occurrences, respectively; 9 vs 11; 3 vs 5; when summed, intergroup difference p < 0.05). Secondary peripheral occlusive arterial disease variables became highly significant versus aspirin (p < 0.001 or greater) at 3 and 6 months after treatment. The duration of lysis was markedly shorter upon addition of abciximab versus aspirin (75 vs 110 min; p < 0.001). No major bleeding complications or embolisms occurred. These preliminary results indicate that abciximab may have a useful role when used adjunctively with a thrombolytic agent in older persons with acute peripheral occlusive arterial disease and arterial thrombosis.