Embolization of tumor cells is rare in patients with systemic cancer and cerebral large vessel occlusion.

BACKGROUND AND PURPOSE: Stroke is a dreaded complication in patients with cancer. Besides paraneoplastic coagulopathy, chemotherapy, radiotherapy and tumor-directed invasive procedures, circulating cancer cells may contribute to thrombus formation and embolic stroke. However, the incidence of tumor cells within the blood clots of cancer patients with stroke is unknown and the role of circulating tumor cells in the formation of cerebrovascular thrombi remains unclear. METHODS: All patients who had undergone cerebrovascular thrombectomy at the University Hospital Zurich between 2014 and 2017 were screened for history of cancer. Clinical information was retrieved from the local stroke registry and the electronic charts and thrombi underwent a thorough histopathological re-review. RESULTS: Thirty-two of 182 patients (18%) with thrombectomy had a history of cancer. The majority of patients had advanced stage cancer. However, even after extensive histopathological re-review, only one specimen revealed tumor cells in the thrombus: a 75-year-old patient with acute occlusion of the middle cerebral artery who had been diagnosed with non-small-cell lung cancer 8.1 months prior to stroke. CONCLUSIONS: The presence of cancer cells in clots from cerebrovascular thrombectomy, indicative of a direct involvement of circulating tumor cells in the causation of stroke, is rare.

Mutations in the hair cortex keratin hHb6 cause the inherited hair disease monilethrix.

Pathogenic mutations in a large number of human epithelial keratins have been well characterized. However, analogous mutations in the hard alpha-keratins of hair and nail have not yet been described. Monilethrix is a rare autosomal dominant hair defect with variable expression. Hairs from affected individuals show a beaded structure of alternating elliptical nodes and constrictions (internodes). These internodes exhibit a high prospensity to weathering and fracture. Strong evidence that trichocyte keratin defects might underlie this hair disorder was provided by genetic linkage analyses that mapped this disease to the type-II keratin gene cluster on 12q13. All affected individuals from a four-generation British family with monilethrix, previously linked to the type-II keratin gene cluster, as well as three unrelated single monilethrix patients, exhibited a heterozygous point mutation in the gene for type-II hair cortex keratin hHb6, leading to lysine substitution of a highly conserved glutamic acid residue in the helix termination motif (Glu 410 Lys). In a three-generation French family with monilethrix of a milder and variable phenotype, we detected another heterozygous point mutation in the same glutamic acid codon of hHb6, which resulted in a conservative aspartic acid substitution (Glu 410 Asp). These mutations provide the first direct evidence for involvement of hair keratins in hair disease.

Recurrent abdominal pain in 200 children: somatic causes and diagnostic criteria.

AIM: To establish to what extent somatic causes can be found in children referred to secondary care with recurrent abdominal pain. METHODS: For 2 years, all consecutive patients (age 4-16 years) fulfilling Apley criteria, referred to secondary care, were included. After a diagnostic work-up, stepwise therapeutic interventions were performed. A diagnosis was considered to be the cause of the pain when the patient became pain free following therapeutic intervention and remained so for at least 6 months. RESULTS: Two hundred and twenty children (128 F, 92 M; mean age 8.8 years) were enrolled, of which 20 were lost to follow-up. Spontaneous recovery was seen in 54 patients, (occult) constipation in 92 patients (of whom 18 also had a somatic cause), gastrointestinal infections in 40, food allergy in five, miscellaneous disorders in seven and uncertain diagnosis in 13. In five patients, stress most likely caused the pain. A total of 198 patients became pain free and remained so during follow-up (mean 18, range 6-60 months). CONCLUSION: In 200 children with recurrent abdominal pain, somatic causes were found in 26%. Laxative therapy was successful in 46%, resulting in nearly all patients with functional abdominal pain to become pain free. Eventually, 99% became pain free using a therapeutic intervention protocol.

Differential localization of distinct keratin mRNA-species in mouse tongue epithelium by in situ hybridization with specific cDNA probes.

The tongue of the adult mouse is covered by a multilayered squamous epithelium which is continuous on the ventral surface, however interrupted on the dorsal surface by many filiform and few fungiform papillae. The filiform papillae themselves are subdivided into an anterior and posterior unit exhibiting different forms of keratinization. Thus, the entire epithelium shows a pronounced morphological diversity of well recognizable tissue units. We have used a highly sensitive in situ hybridization technique to investigate the differential expression of keratin mRNAs in the tongue epithelium. The hybridization probes used were cDNA restriction fragments complementary to the most specific 3'-regions of any given keratin mRNA. We could show that independent of the morphologically different tongue regions, all basal cells uniformly express the mRNA of a type I 52-kD keratin, typical also for basal cells of the epidermis. Immediately above the homogenous basal layer a vertically oriented specialization of the keratin expression occurs within the morphological tissue units. Thus the dorsal interpapillary and ventral epithelium express the mRNAs of a type II 57-kD and a type I 47-kD keratin pair. In contrast, in the anterior unit of the filiform papillae, only the 47-kD mRNA is present, indicating that this keratin may be coexpressed in tongue epithelium with different type II partners. In suprabasal cells of both, the fungiform papillae and the posterior unit of the filiform papillae, a mRNA of a type I 59-kD keratin could be detected; however, its type II 67-kD epidermal counterpart seems not to be present in these cells. Most surprisingly, in distinct cells of both types of papillae, a type I 50-kD keratin mRNA could be localized which usually is associated with epidermal hyperproliferation. In conclusion, the in situ hybridization technique applied has been proved to be a powerful method for detailed studies of differentiation processes, especially in morphologically complex epithelia.

[Pacemaker and implantable defibrillators with telemedical support]. / Schrittmacher und interne Defibrillatoren mit kardiotelemedizinischer Unterstützung.

Recent developments in pacemaker and ICD therapy can be characterized by a rising number of implantations (especially in the field of ICD and CRT systems) and an increasing complexity of the units involved. Problems evolving from this trend are the soaring numbers of necessary follow-up examinations, issues of patient safety and the necessity of device management by specialized physicians. Telemonitoring offers various possibilities of improvement in these areas. The manufacturers of the devices have developed applicable solutions for concepts of care including telemedical monitoring of patients with pacemakers, ICD and CRT systems. The systems commonly include an implant capable of either automatic or manual data transmission, a device for transmitting the implant's data (mobile communication or fixed line network), a server managing the information and a front-end (internet-based) platform for the physician. Multiple clinical trials have verified the stability and the security of this method of data transmission. Telemedical monitoring can be used in order to improve the monitoring of the patients' state of health (e. g., patients with CRT systems because of their CHF) and the management of arrhythmias (e. g., patients suffering from paroxysmal atrial fibrillation). Telemonitoring allows the intervals between follow-up check-ups to be individualized, thus, leading to financial savings. The telemedical monitoring of patients with ICD and CRT systems facilitates new opportunities for networked follow-up care and comprehensive medical treatment.

Depression of spinal network activity by thiopental: shift from phasic to tonic GABA(A) receptor-mediated inhibition.

Interneuronal networks in the spinal ventral horn are plausible substrates for mediating anesthetic-induced immobility. Here, we investigated how their activity is affected by clinically relevant concentrations of thiopental, a barbiturate in clinical use. In cultured spinal cord slices from mice, thiopental reduced action potential activity with an EC(50) of 16.6+/-2.4microM. Recordings of GABA(A) and glycine receptor-mediated inhibitory currents indicated that the effect was largely mediated by GABA(A) receptors and that glycine receptors were not relevant targets. Specifically, 20microM thiopental prolonged the decay time of spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs) more than twofold. Although this prolongation of decay time increased the inhibitory charge per sIPSC the concomitant strong reduction of sIPSC frequency resulted in less inhibitory current entering the neurons via this route. However, 20microM thiopental also induced a tonic current of 30+/-10pA, mediated by GABA(A) receptors; 50microM thiopental nearly abolished sIPSC activity but augmented tonic currents to 69+/-14pA. Furthermore, at this concentration, activity-depressing mechanisms independent of GABA(A) receptors came into play. The results suggest that in the spinal ventral horn thiopental acts mostly, but not exclusively, via GABA(A) receptors. With increasing concentrations of the drug, inhibition via sIPSCs is limited by negative feedback on interneuronal firing whereas action potential-independent GABAergic inhibition due to tonic currents gains progressively in impact.

Abnormal liver enzymes two years after haematopoietic stem cell transplantation in children: prevalence and risk factors.

To establish the prevalence of elevated liver enzymes in children transplanted in a Dutch haematopoietic stem cell transplantation (HSCT) centre, we retrospectively assessed AST and ALT values at 2 years after HSCT. Age, sex, diagnosis, type of transplant, conditioning regimen and early post-transplant complications involving the liver (veno-occlusive disease, acute GVHD, viral reactivation) were analysed as risk factors. AST and ALT values were available at 2 years after HSCT in 216 of 290 patients (75%) alive at that time and were above normal in 53 (25%) and at least twice normal in 17 (8%) patients. Older age at HSCT and a diagnosis of benign haematological disease are risk factors for abnormal liver enzymes late after HSCT. In half of the patients with benign haematological disease, iron overload is the most likely aetiological factor. Chronic hepatitis B or C is uncommon in our centre. In conclusion, the prevalence of abnormal liver enzymes late after HSCT in our centre is lower than reported in previous studies. Abnormal liver enzymes occur more often in children who are older at HSCT and transplanted for benign haematological disease. Long-term follow-up is crucial to establish if elevated liver enzymes precede clinical liver disease.

New concepts on the histogenesis of eccrine neoplasia from keratin expression in the normal eccrine gland, syringoma and poroma.

BACKGROUND: Peripheral and luminal layers of eccrine sweat gland ducts are self-renewing structures. Proliferation is restricted to the lowermost luminal layer, but randomly scattered in the peripheral layer. Each layer exhibits differential expression of keratins K5/K14 and K6/K16. Keratin K1 occurs only in peripheral cells and the novel keratin K77 is specific for luminal cells. OBJECTIVES: To investigate the expression of luminal (K77), peripheral (K1) and further discriminatory keratins in two eccrine sweat gland tumours: syringoma, thought to show differentiation towards luminal cells of intraepidermal sweat ducts and eccrine poroma, considered to arise from poroid cells, i.e. peripheral duct cells; and keratinocytes of the lower acrosyringium/sweat duct ridge differentiating towards cells of intradermal/intraepidermal duct segments. METHODS: Paraffin-embedded sections were examined by immunohistochemistry using several keratin, smooth muscle actin and Ki-67 antibodies. RESULTS: We confirmed the ductal nature of syringomas. Despite drastic morphological alterations in both layers, their keratin patterns remained almost undisturbed compared with normal ducts. In eccrine poroma epidermal keratins K5/K14 were ubiquitously expressed in all poroid cells. Cell islands deviating morphologically from poroid cells contained epidermal keratins K1/K10. K77 expression was limited to luminal cells of intact duct structures within the tumours. CONCLUSIONS: Syringomas are benign tumours of luminal cells of the lowermost intraglandular sweat duct. Poroid precursor cells of poromas do not comprise peripheral duct cells nor do poromas differentiate towards peripheral or luminal duct cells. Instead, poroid cells consist only of keratinocytes of the lowermost acrosyringium and the sweat duct ridge and poromas tend to differentiate towards the cells of the upper acrosyringium.

HPV E6 oncoproteins and nucleic acids in neck lymph node fine needle aspirates and oral samples from patients with oropharyngeal squamous cell carcinoma.

Commercial assays measuring HPV E6 viral oncoproteins, E6/E7 mRNA or DNA were used to test neck lymph node fine needle aspirates (FNA) and oropharyngeal samples (saliva and oral swabs) from 59 Canadian patients with oropharyngeal squamous cell carcinomas (OPSCC). Overall agreements of p16 antigen staining of tumors to FNA tested for OncoE6™, Aptima HPV E6/E7 mRNA and cobas HPV DNA were 81.4% (k 0.53), 94.9% (k 0.83) and 91.1% (k 0.73) respectively. Using HPV presence in a subset of 25 tumors as the comparator, overall agreement was 64.0% (k 0.08) with OncoE6™, 88.0% (k 0.65) with Aptima HPV E6/E7 mRNA and 91.7% (k 0.70) with cobas HPV DNA. HPV testing of oropharyngeal samples yielded lower agreements with tumor markers; 23.7-24.0% (k 0.02), 55.9-68.0% (k 0.24-0.37) and 78.9-86.9% (k 0.49-0.58) in the 3 respective tests. HPV 16 was present in 93.7-100% of the samples tested and showed 100% genotype agreement between FNA and tumors. The high rates for HPV E6 oncoproteins and E6/E7 mRNA suggests most patients were experiencing transcriptionally active HPV-related OPSCC. Results from these commercial assays performed on FNA but not oropharyngeal samples showed moderate to very good agreements with p16 and HPV testing of tumors.

Induction of the formation of new hair follicles in mouse tail epidermis by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate.

The formation of new hair follicles was quantitatively demonstrated in the tail skin of adult mice in the course of a two-stage carcinogenesis experiment with 7,12-dimethylbenz(a)anthracene as an initiator and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate as a promoter, as well as in experiments with 12-O-tetradecanoylphorbol-13-acetate alone. Two kinds of follicular neogenesis could be distinguished. The most frequently encountered type was characterized by the organization of new follicles from the upper neck and orifice regions of already existing follicles. During their development, these new follicles remained in close apposition to the original follicles but, after having reached a critical size, split off to form fully independent follicles. In the second, type of follicular neogenesis, which occurred very rarely, the new follicles seemed to arise directly from the epidermis between two sets of hair triads; however, these follicles never reached their final stage and did not produce hairs. The formation of new hair follicles may be explained by a "dedifferentiation" of epidermal cells caused by the tumor promoter. Because of the paucity and advanced stage of the papillomas formed in tail skin after long-term treatment with 12-O-tetradecanoylphorbol-13-acetate, no reliable comment as to whether the papillomas derive from the hair follicles can be made.

Histological, proliferative, and biochemical alterations in dorsal epidermis of the Syrian golden hamster induced by 12-O-tetradecanoylphorbol-13-acetate and the calcium ionophore A 23187.

Long-term treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) of dorsal skin of 7,12-dimethylbenz(a)anthracene-initiated Syrian golden hamsters does not lead to the formation of epithelial tumors and leaves the epidermis essentially unchanged. However, previous histological studies by others have shown that hamster epidermis can be hyperplastically transformed by a single application of TPA but that the tissue is capable of gradually adapting to the drug after extended TPA exposure. We have investigated the response of hamster back epidermis to single and multiple treatments with increasing doses of TPA with regard to histological, proliferative, and biochemical alterations, and we show that in our animal strain the dorsal epidermis is resistant to even a single exposure to TPA, although the clearance rate of TPA is comparable to that in mouse epidermis and the metabolism of the substance is negligible. In contrast, the epidermis could be moderately stimulated by a single application of the nonpromoting calcium ionophore A 23187 and exhibited a strong proliferate and hyperplastic response following the simultaneous exposure to the calcium ionophore and TPA. Both types of hyperproliferation did not reveal an initial depression of the proliferative activity and were accompanied by typical alterations of the keratin polypeptide pattern, which was not detectable after treatment with TPA alone.

Systemic two-stage carcinogenesis in the epithelium of the forestomach of mice using 7,12-dimethylbenz(a)anthracene as initiator and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate as promoter.

In a modified two-stage carcinogenesis experiment, the effectiveness of the initiator 7,12-dimethylbenz(a)anthracene (DMBA) and the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) in the epithelium of the forestomach of the mouse has been investigated. Fifty mice were treated intragastrically with a single dose of DMBA (50 mg/kg body weight), followed by repeated intragastric administration of TPA (10 mg/kg body weight) over a period of 35 weeks. In comparison with the corresponding control groups (no treatment, DMBA initiation only, and TPA treatment only), the initiated and promoted group clearly showed the highest tumor incidence in the target organ (45 tumor-bearing animals of 50 animals). No tumors of the forestomach were found in the untreated control group and the TPA-treated group, whereas in the DMBA-initiated group, ten animals had developed tumors of the forestomach. In addition to the mouse skin model for two-stage carcinogenesis, the mouse forestomach appears to respond to DMBA initiation-TPA promotion. This organ provides an additional tissue with which to investigate tumor promotion and further to ascertain specific parameters of the promotion step.

Carcinogen-specific mutational pattern in the p53 gene in ultraviolet B radiation-induced squamous cell carcinomas of mouse skin.

We have examined 35 epidermal tumors induced in mice of four different strains by chronic exposure to ultraviolet B radiation for the presence of aberrations in the p53 tumor suppressor gene. Polymerase chain reaction products from p53 exons 5 to 8 were screened by single-strand conformation polymorphism analysis and sequencing. Base substitutions were found in seven tumors (20%). All mutations occurred at dipyrimidine sequences; most frequent were C-->T single base and CC-->TT tandem transitions suggesting the involvement of UV radiation in the genesis of the mutations. Three base substitutions were located at codon 148, and all dipyrimidine-derived mutations occurred at sites where the sequence is present in the nontranscribed DNA strand, indicating some site and strand specificity of the ultraviolet B-induced p53 mutations.

A cDNA encoding the human type I hair keratin hHal.

A full-length cDNA of a human type I hair keratin was isolated that encodes a protein of 416 amino acids. Northern blot analysis shows that the mRNA is present in human scalp but not in hairless skin. Based on sequence homology comparisons with the four known mouse type I hair keratins mHal-4 the keratin could be identified as the human hair keratin hHal.

Effect of high dose verapamil on restenosis after peripheral angioplasty.

OBJECTIVES: We sought to determine whether treatment with high dose verapamil prevents restenosis in patients at high risk for reoccurrence after successful percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Restenosis is the major limitation of PTCA. Calcium antagonists have demonstrated some potential as inhibitors of this process. METHODS: A total of 98 patients with peripheral occlusive arterial disease (POAD), stable angina pectoris, mild hypertension and at least one additional risk factor increasing the likelihood of restenosis after angioplasty were selected for this placebo-controlled, double-blind, randomized trial. Verapamil (240 mg twice daily) or placebo was taken for 6 months. Efficacy variables assessed before and after angioplasty and at 6 weeks and 6 months after PTCA included thickness of the intima/media complex degree of stenosis, interventricular septal thickness, crurobrachial pressure ratios of dorsalis pedis and posterior tibial arteries, distance to claudication and total vessel diameter. RESULTS: No significant intergroup differences emerged before or immediately after PTCA. Six weeks after angioplasty, a significant thickening of the intima/media complex in the treated vascular segment of 14.3% occurred in the placebo group versus 0% among verapamil patients (p < 0.01). At 6 months, the intima/media thickness was 35.7% greater in the placebo group but had decreased by 14.3% in the verapamil group (p < 0.001). At 6 months, a marked reduction in septal thickness was observed in the verapamil group versus that in the placebo group (p < 0.001). The rate of restenosis was also significantly lower in the verapamil group (p < 0.001). Few minor side effects were reported. CONCLUSIONS: In patients with POAD at increased risk for restenosis, the administration of high dose verapamil prevented recurrent stenosis for 6 months after successful peripheral angioplasty and was well tolerated.

Short- and long-term results after thrombolytic treatment of deep venous thrombosis.

OBJECTIVES: The goal of this study was to assess the short- and long-term efficacy of different thrombolytic therapy regimens in patients with leg or pelvic deep venous thrombosis (DVT). BACKGROUND: It is unclear whether locoregional or systemic thrombolysis is superior in treating acute leg DVT or even whether lysis is more effective than anticoagulation therapy in preventing postthrombotic syndrome. METHODS: A total of 250 patients averaging 40 years of age with acute DVT were randomized into five groups to receive full heparinization (1,000 IU/h) and compression treatment, with four groups also administered locoregional tissue plasminogen activator (20 mg/day) or urokinase (100,000 IU/day) or systemic streptokinase (3,000,000 IU daily) or urokinase (5,000,000 IU daily). All groups then received anticoagulation and compression treatment for one year. Primary efficacy criteria included the change after one year in the number of closed vein segments and the occurrence of postthrombotic syndrome. RESULTS: Systemic thrombolytic therapy significantly reduced the number of closed vein segments after 12 months in patients with acute DVT compared with conventional treatment (p < 0.05). Postthrombotic syndrome also occurred with less frequency in systemically treated patients versus controls (p < 0.001). High-dose thrombolysis led to better rates of complete recanalization after seven days (p < 0.01) than locoregional lysis. However, 12 patients receiving thrombolysis (9 systemic, 3 local) suffered major bleeding complications; 9 patients on systemic treatment developed pulmonary emboli. CONCLUSIONS: Systemic thrombolytic treatment for acute DVT achieved a significantly better short- and long-term clinical outcome than conventional heparin/anticoagulation therapy but at the expense of a serious increase in major bleeding and pulmonary emboli. Given the inherent risks for such serious complications, systemic thrombolysis, although effective, should be used selectively in limb-threatening thrombotic situations.

Candesartan treatment for peripheral occlusive arterial disease after stent angioplasty : a randomised, placebo-controlled trial.

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.

The large type II 70-kDa keratin of mouse epidermis is the ortholog of human keratin K2e.

The basic keratin pattern of mammalian epidermis consists of the basal keratin pair K5/K14 and the differentiation-specific keratin pair K1/K10. Distinct skin sites of the adult mouse, i.e., ear, sole of the foot, and interscale regions of tail skin, express an additional, type II 70-kilodalton (kDa) keratin without a defined new type I partner in suprabasal epidermal cells. Until now, the question whether this large keratin is specific for the mouse (or related small rodents) or whether orthologous keratins exist in other species has not yet been answered. In the present study, we have determined the full-length amino acid sequence of the 70-kDa keratin. The keratin comprises 707 amino acid residues and has a calculated molecular weight of 70,976.70 Da. From the structural point of view, the 70-kDa keratin is remarkable in that more than half of both the V1 and V2 subdomains of its non alpha-helical head and tail portions consist of different glycine-rich peptide motifs that are configured consecutively at least two times and as much as seven times in tandem. By means of sequence comparisons and phylogenetic investigations, we show that the 70-kDa keratin represents the murine ortholog of the human 65-kDa keratin K2e, whose nature as a genuine keratin has recently been demonstrated. The unusually large size difference of 5 kDa between MK2e and HK2e is due mainly to a different duplication rate of the glycine-rich peptide motifs in the respective V subdomains of the orthologous keratins. We discuss the properties of these highly specialized keratins, which in both species define locally restricted epidermal keratin phenotypes, and compare them with other orthologous keratins that belong to the basic epidermal keratin pattern.

Selective suppression of two postnatally acquired 70 kD and 65 kD keratin proteins during continuous treatment of adult mouse tail epidermis with vitamin A.

Using mouse tail epidermis as a model system we have studied the morphologic and biochemical effects of continuous topical treatment with vitamin A acid. Normal tail epidermis shows a regular pattern of parakeratotic scale regions and orthokeratotic interscale regions which arise postnatally from a uniformly orthokeratinizing neonatal epidermis. Daily treatment of tail epidermis with vitamin A acid for 14 days results in the induction of hyperplasia and the orthokeratotic conversion of the scale regions. The degree of these alterations is dose-dependent and maximally brought about by repetitive 30-microgram doses of the vitamin. To correlate morphologic with biochemical alterations, we have analyzed the keratin patterns of normal and vitamin A acid-treated epidermis by one- and two-dimensional gel electrophoresis. The results indicate that repetitive vitamin A treatment leads to the selective suppression of two postnatally acquired 70 kD and 65 kD type II keratin proteins. Again the minimum repetitive dose required for their complete suppression is 30 micrograms vitamin A acid. Kinetic studies reveal an initial lag phase of 6 days of apparent nonresponsiveness, followed by a 5-day period during which the adult pattern is gradually replaced by the neonatal pattern. Repetitive treatment of tail epidermis with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate leads to a strong hyperplasia; however, it strictly maintains the scale parakeratosis. Under these conditions only the 70 kD keratin subunit is suppressed. This indicates that the suppression of the 70 kD keratin is generally linked to the induction of hyperproliferation, whereas the suppression of the scale-associated 65 kD subunit is due to the metaplastic potency of vitamin A. We provide evidence that this vitamin A-specific in vivo effect can be used to determine the biologic activity of synthetic retinoids relative to vitamin A acid.