Utilization of a mouse/human chimeric model for long term metabolic testing of human skin

Until now, ex vivo human skin explant utilization in tissue culture has consisted of limited short-term studies (less than a week). This short timeframe does not allow for the investigation of metabolic responses of complex tissues to specific molecules or compounds. Here, we aim to develop an improved mouse transplantation model that maintains the viability, structure and functionality of the human skin explants for prolonged periods of time. Healthy human skin explants derived from biopsies were grafted onto nude mice and used to perform a toxicological study of the reactivity and functionality of grafted skin explants after one month. Histological observations suggest that the tissue properties and phenotype of the human skin graft are conserved as a result of re-vascularization upon tissue integration. The toxicological test performed shows that the human skin graft reacts to systemic exposure of a xenobiotic metabolic inducer when applied to this mouse model. This mouse/human chimeric model can be effective for the long-term study of human skin reactivity to chemicals as well to study in vivo responses to complex co-exposures.

Tumor progression of skin carcinoma cells in vivo promoted by clonal selection, mutagenesis, and autocrine growth regulation by granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor

Tumor microenvironment is crucial for cancer growth and progression as evidenced by reports on the significance of tumor angiogenesis and stromal cells. Using the HaCaT/HaCaT-ras human skin carcinogenesis model, we studied tumor progression from benign tumors to highly malignant squamous cell carcinomas. Progression of tumorigenic HaCaT-ras clones to more aggressive and eventually metastatic phenotypes was reproducibly achieved by their in vivo growth as subcutaneous tumors in nude mice. Their enhanced malignant phenotype was stably maintained in recultured tumor cells that represented, identified by chromosomal analysis, a distinct subpopulation of the parental line. Additional mutagenic effects were apparent in genetic alterations involving chromosomes 11 and 2, and in amplification and overexpression of the H-ras oncogene. Importantly, in vitro clonal selection of benign and malignant cell lines never resulted in late-stage malignant clones, indicating the importance of the in vivo environment in promoting an enhanced malignant phenotype. Independently of their H-ras status, all in vivo-progressed tumor cell lines (five of five) exhibited a constitutive and stable expression of the hematopoietic growth factors granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor, which may function as autocrine/paracrine mediators of tumor progression in vivo. Thus, malignant progression favored by the in vivo microenvironment requires both clonal selection of subpopulations adapted to in vivo growth and mutational events leading to stable functional alterations.

Human mast cells activate fibroblasts: tryptase is a fibrogenic factor stimulating collagen messenger ribonucleic acid synthesis and fibroblast chemotaxis

The effect of human mast cells on fibroblast activity was studied using an organotypic skin-equivalent culture system. Human mast cell-1 (HMC-1) cells were embedded in a collagen gel with neonatal dermal fibroblasts at a ratio of 1:4; keratinocytes then were allowed to stratify above this composite culture. Analysis of type a1(I) procollagen mRNA synthesis by in situ hybridization revealed a substantial increase in mRNA levels in the presence of mast cells and especially following degranulation, induced by calcium ionophore A23187. Tryptase, a major product of human mast cells, could substitute for mast cells in this culture system, up-regulating procollagen mRNA synthesis. Tryptase pretreated with the specific protease inhibitor bis(5-amidino-2-benzimidazo-lyl)methane (BABIM) markedly attenuated the collagen mRNA up-regulation. Further studies revealed HMC-1 cell sonicates stimulated fibroblast chemotaxis and procollagen mRNA synthesis. Inhibition of HMC-1 sonicates with either BABIM or a neutralizing mAb against tryptase resulted in significant reduction of fibroblast chemotaxis and procollagen mRNA, implying that tryptase accounted for the majority of HMC-1 sonicate activity. Tryptase directly stimulated fibroblast chemotaxis with optimal concentrations between 10 pM and 1 nM. The maximal response of optimal concentrations of tryptase was comparable with the known fibrogenic factor, TGF-beta. Inhibition of tryptase with BABIM resulted in approximately 50% reduction in chemotactic activity. Additional studies revealed that tryptase (0.3-3 nM) stimulated procollagen mRNA synthesis in confluent monolayers of dermal fibroblasts.

Human mast cells activate fibroblasts: tryptase is a fibrogenic factor stimulating collagen messenger ribonucleic acid synthesis and fibroblast chemotaxis

The effect of human mast cells on fibroblast activity was studied using an organotypic skin-equivalent culture system. Human mast cell-1 (HMC-1) cells were embedded in a collagen gel with neonatal dermal fibroblasts at a ratio of 1:4; keratinocytes then were allowed to stratify above this composite culture. Analysis of type a1(I) procollagen mRNA synthesis by in situ hybridization revealed a substantial increase in mRNA levels in the presence of mast cells and especially following degranulation, induced by calcium ionophore A23187. Tryptase, a major product of human mast cells, could substitute for mast cells in this culture system, up-regulating procollagen mRNA synthesis. Tryptase pretreated with the specific protease inhibitor bis(5-amidino-2-benzimidazo-lyl)methane (BABIM) markedly attenuated the collagen mRNA up-regulation. Further studies revealed HMC-1 cell sonicates stimulated fibroblast chemotaxis and procollagen mRNA synthesis. Inhibition of HMC-1 sonicates with either BABIM or a neutralizing mAb against tryptase resulted in significant reduction of fibroblast chemotaxis and procollagen mRNA, implying that tryptase accounted for the majority of HMC-1 sonicate activity. Tryptase directly stimulated fibroblast chemotaxis with optimal concentrations between 10 pM and 1 nM. The maximal response of optimal concentrations of tryptase was comparable with the known fibrogenic factor, TGF-beta. Inhibition of tryptase with BABIM resulted in approximately 50% reduction in chemotactic activity. Additional studies revealed that tryptase (0.3-3 nM) stimulated procollagen mRNA synthesis in confluent monolayers of dermal fibroblasts.

Initial training as a stimulus for optimal physical fitness in firemen

In this investigation the physical fitness of 34 recruits to the UK Fire Service was assessed before and after their initial training (tests 1-2) and on three occasions (tests 3-5) during the first 18 months of their service (n = 34 + 6 = 40). The initial training (test 2-test 1) resulted in an increase in maximum aerobic power (11% p < 0.05), body mass (2 kg, p < 0.001), lean body mass (2.02 kg, p < 0.001), grip and lifting strengths (p < 0.001), and in calf girth (p < 0.05). But no change in waist girth, maximum anaerobic power or measures of lung function was noted. There was evidence therefore that the men became physically fitter. In the first eighteen months of their service, subjects' maximum oxygen consumption declined to pre-training levels, while body mass continued to increase with a decrease in lean body mass (p < 0.001). Strength remained unaltered or tended to fall with a decrease in calf girth (p < 0.05). These changes reflected a return towards pre-training physical fitness levels. It is suggested that the initial training, while ill-matched to the firemen's habitual activity, produced levels of physical fitness which may approximate more closely to the infrequent peak requirements experienced by the men during actual fire fighting. Consequently it is concluded that the physical training during service was insufficiently intense and that a more effective programme could be designed to maintain an appropriate level of physical fitness.

Head and neck manifestations of tumoral calcinosis

Intraoral facial and laryngeal features of tumoral calcinosis are reviewed in six patients of Jewish-Yemenite descent. Extraoral features included calcified masses, erythematous patches, and angular cheilitis. Oral soft tissue findings included papillary hyperplasia of the lip vermilion and velvety-red macules on the tongue, palate, and buccal mucosa. Gingival findings included advanced periodontitis and an erythematous marginal gingivitis. In all patients, orthognathic evaluation revealed a concave profile, retruded maxilla, and relative mandibular prognathism. Although previously reported clinical dental abnormalities were not present, extracted teeth demonstrated abnormal dentin. Hoarseness was present in all patients and was the earliest appearing feature in two patients. The appearance of these head and neck findings preceded the classical manifestations of tumoral calcinosis and may be helpful in the early diagnosis of this entity. The varied reported features of tumoral calcinosis support the notion that this disease may present multiple formes frustes with variable clinical expressivity.

Touton-like giant cells in periapical granulomas

Two types of multinucleated giant cells were observed in periapical granulomas--the foreign body type and the Touton type. In the Touton type, the nuclei were near the center of the cell, surrounded by foamy cytoplasm. Both types of giant cells reacted positively to lysozyme, alpha 1-antitrypsin and alpha 1-antichymotrypsin, indicating their histiocytic origin.

Aneurysmal bone cyst of the mandible

The case of a 48-year-old male patient with a slowly growing mass in the right molar region of the mandible is presented. The biopsy specimen showed an aneurysmal bone cyst. After radiation therapy failed to arrest the process, the patient was treated surgically via an external approach. Between the time of the initial presentation and the date of definitive surgery 9 months later, a dramatic change was noted in the roentgenographic pattern of the lesion, demonstrating early and late stages in the development of an aneurysmal bone cyst. There has been no recurrence in a 17-year follow-up period.

The role of spinal cord transmission in the ventilatory response to exercise in man

The ventilatory response to electrically induced exercise was studied in thirteen patients with traumatic spinal cord transection at or about the level of T6. The steady-state and on-transient responses to this exercise were compared with those obtained in eighteen normal subjects (Adams, Garlick, Guz, Murphy & Semple, 1984). Exercise was produced by surface electrode stimulation of the quadriceps and hamstring muscles so as to produce a pushing movement at 1 HZ against a spring load. At rest there was no significant difference between normals and patients, except that the patients had a lower CO2 elimination (VCO2) and end-tidal PCO2 (PET,CO2) and a higher heart rate. On exercise the mean rise in VCO2 for the patients was 172 ml min-1 (S.D. 72), and for the normals was 287 ml min-1 (S.D. 143). The corresponding mean changes in ventilation (VI) were 4.4 l min-1 (S.D. 2.2) and 7.6 l min-1 (S.D. 3.2). However, the ventilatory equivalent for CO2 (delta VI/delta VCO2) in the steady state was not significantly different between patients (26.0, S.D. 5.9) and normals (28.5, S.D. 7.4). In the steady state there was a mean rise in PET,CO2 of 0.9 mmHg (S.D. 1.4) in the normals, and 3.2 mmHg (S.D. 2.7) in the patients, but there was overlap between the two groups. In many experimental runs in both groups, PET,CO2 did not rise, and sometimes fell. Where PCO2 did rise, the ventilatory response to exercise could not be accounted for on the basis of the ventilatory sensitivity to CO2 inhalation. From arterial sampling in three of the patients it was found that when PET,CO2 rose, the corresponding change in Pa,CO2 was less. During the on transient, there was a significant rise in both VCO2 and VI by the second breath in both groups. At the end of the on transient the normal subjects had achieved 84% (S.D. 40) of the steady-state increase in VCO2 and 88% (S.D. 24) of the increase in VI. The corresponding values for the patients were 67% (S.D. 17) and 77% (S.D. 16) respectively; these differences between normals and patients are significant. The increase of VI during the on transient in the patients was achieved almost entirely by an increase in tidal volume whereas in normals, an increase in respiratory rate was a more important component. We conclude therefore that in man, spinal cord transection with a presumed loss of muscle afferents allows a ventilatory response to electrically induced exercise that cannot be explained by classical chemoreception.(ABSTRACT TRUNCATED AT 400 WORDS)

Is the voluntary control of exercise in man necessary for the ventilatory response?

The ventilatory response to electrically induced exercise (EEL) was studied in eighteen normal subjects and compared with the response to performing the same exercise voluntarily (EV). EEL was produced by surface electrode stimulation of the quadriceps and hamstring muscles so as to cause a pushing movement at 1 HZ against a spring load; this produced no pain or discomfort. Matching of EV to EEL was achieved by subjects copying a tension signal recorded during EEL and displayed on a storage oscilloscope. There were no differences between the resting states measured before either form of exercise. The ventilatory response (change in ventilation as a ratio of the change in CO2 elimination) was similar in the two types of exercise. The increases in ventilation and CO2 elimination were greater with EEL. Small but significant increases in the gas exchange ratio and serum lactate were found for EEL but not for EV, suggesting an increase in anaerobic metabolism in EEL. End-tidal PCO2 showed little change in either form of exercise. In some runs end-tidal PCO2 rose, but insufficiently to account for the ventilatory response as judged by the response to inhaled CO2. In two subjects arterial blood samples showed small and inconsistent changes in both Pa,CO2 and PaO2 for EV and EEL. pH and base excess changes also were consistent with more anaerobiosis with EEL compared to EV. The first ten breaths of exercise were used to study the on transient. In EV, expiratory duration shortened and ventilation increased significantly on the first breath but CO2 elimination did not increase until the second breath; in EEL, these variables did not change significantly until the second breath. For the remainder of the on transient the pattern of the ventilatory response was similar for EV and EEL. By the end of the on transient both EV and EEL had reached approximately 80% of their final steady-state values. These results suggest that a normal ventilatory response can occur in the absence of a drive to exercise from the cortex.

Activities of haem synthetic enzymes in blood cells of pre-natal flexed-tailed (f/f) anaemic mice

Levels of activity of δ-aminolaevulinate synthetase, δ-aminolaevulinate dehydratase, porphyrinogen synthetase and haem synthetase in circulating reticulocytes of pre-natal FL4/Re +/+ and congenitally anaemic FL1/Re ƒ/ƒ mice have been determined. The activities of δ-aminolaevulinate synthetase and δ-aminolaevulinate dehydratase were found to be decreased in proportion to the hypochromia observed in mature liver-derived erythrocytes in neonatal ƒ/ƒ mice, but activities of enzymes later in the haem synthetic pathway were relatively undisturbed. No significant differences were found in levels of haem synthetic enzymes in foetal livers of +/+ and ƒ/ƒ mice. These results indicate that the severe anaemia of late prenatal and neonatal ƒ/ƒ mice is due both to reduction in haem synthesis expressed at the reticulocyte stage of erythroid differentiation and to restricted production of erythroid progenitor cells. Retarded foetal growth and skeletal abnormalities, both characteristic of the pre-natal expression of the ƒ/ƒ gene complement, can also be related to reduced levels of haem synthesis, but the abnormal distribution of pigment cells seen in ƒ/ƒ animals appears to be a secondary effect of reduced tissue oxygenation resulting from pre-natal anaemia.

Activities of haem synthetic enzymes in blood cells of pre-natal flexed-tailed (f/f) anaemic mice

Levels of activity of beta-aminolaevulinate synthetase, delta-aminolaevulinate dehydratase, porphyrinogen synthetase and haem synthetase in circulating reticulocytes of pre-natal FL4/Re +/+ and congenitally anaemic FL1/Re f/f mice have been determined. The activities of delta-aminolaevulinate synthetase and delta-aminolaevulinate dehydratase were found to be decreased in proportion to the hypochromia observed in mature liver-derived erythrocytes in neonatal f/f mice, but activities of enzymes later in the haem synthetic pathway were relatively undisturbed. No significant differences were found in levels of haem synthetic enzymes in foetal livers of +/+ and f/f mice. These results indicate that the severe anaemia of late prenatal and neonatal f/f mice is due both to reduction in haem synthesis expressed at the reticulocyte stage of erythroid differentiation and to restricted production of erythroid progenitor cells. Retarded foetal growth and skeletal abnormalities, both characteristic of the pre-natal expression of the f/f gene complement, can also be related to reduced levels of haem synthesis, but the abnormal distribution of pigment cells seen in f/f animals appears to be a secondary effect of reduced tissue oxygenation resulting from pre-natal anaemia.

Disturbed haem and globin synthesis in reticulocytes of prenatal flexed-tailed (f-f) anaemic mice

Haem synthetase activity and co-ordination of α- and β-globin chain synthesis have been investigated in prenatal reticulocytes of congenic FL/4Re +/+Lvb/Lvband FL/1 Ref/f Lvb/Lvb, mice, which have a marked hypochromic, microcytic, siderocytic anaemia, with reduced erythrocyte numbers at birth, and also in other stocks bearing theflesion. Haem synthetase activity inf/freticulocyte homogenates was similar to that in normal cells but was markedly dependent on protoporphyrin added to the homogenate, while activity in normal cell homogenates was relatively independent of added precursor. In cultured normal prenatal reticulocytes α- and β-globin was synthesized in approximately equal amounts during a 4 h labelling period, but inf/freticulocytes there was an approximate 50% deficiency in β-globin chain synthesis. This deficiency could be repaired by added haem but not by protoporphyrin. Such a lesion is quantitatively consistent with the observed hypochromia of neonatalf/ferythrocytes. The relationship of this abnormality to effects of theflocus on early erythropoietic precursor cells is discussed.