Increase In Skin Thickness Research Articles

Use of thigh pressure cuffs to modulate simulated microgravity-induced changes in the skin measured with high-resolution B-scan ultrasound

Objective: The aim of the present study was to evaluate the fluid shift in a simulated microgravity experiment and to test the use of thigh cuffs to help alleviate the problem. Methods: The change in skin thickness was assessed by a 20 MHz B-scan ultrasound device. This was performed on eight volunteers who underwent two successive 7-day periods of −6° anti-orthostatic bed-rest, with or without the daytime use of thigh cuffs. The thigh cuffs were used to counteract the development of facial oedema. Results: In the control group (without thigh cuffs), the results showed a steady increase in skin thickness of the combined dermis and hypodermis of the forehead and a reduction of the thickness of this tissue on the tibia. For the countermeasure group, although thigh cuffs were only employed during the daytime — being removed at night — their use reduced the amplitude and kinetics of the fluid shift, resulting in greater beneficial effects at the end of the day than early in the morning. Conclusion: These results of objective measurements of skin made using a non-invasive high frequency ultrasonography method confirm reports by cosmonauts of a reduction in facial oedema and a more ‘comfortable’ adaptation to microgravity by the use of thigh cuffs during space flight. This system is potentially promising for investigating fluid shifts in the skin and may prove useful in the evaluation of some oedematous skin diseases, as well as their therapy.

Asymmetrical development of bones and soft tissues during eye migration of metamorphosing Japanese flounder, Paralichthys olivaceus.

The symmetrical body of flatfish larvae dramatically changes into an asymmetrical form after metamorphosis. Eye migration results in the most significant asymmetrical development seen in any vertebrate. To understand the mechanisms involved in eye migration, bone and cartilage formation was observed during metamorphosis in laboratory-reared Japanese flounder, Paralichthys olivaceus, by using whole-body samples and histological sections. Most of the hard tissues of the cranium (parasphenoid, trabecular cartilage, supraorbital canal, and supraorbital bar) exist symmetrically in the larval period before metamorphosis and develop by twisting in the same direction as that in which the eye migrates. An increase in skin thickness beneath the eye was observed only on the blind side at the beginning of eye migration; this was the first definitive difference between the right and left sides of the body. The pseudomesial bar, a peculiar bone present only in flatfishes, developed from this thick skin and grew dorsad. Novel sac-like structures were found and named retrorbital vesicles. The retrorbital vesicle of the blind side grew larger and faster than that of the ocular side when the right eye moved most dramatically, whereas no difference was observed between the volume of right and left connective tissue in the head. The asymmetrical presence and growth of the pseudomesial bar together with inflation of the retrorbital vesicle on the blind side may be responsible for right eye migration during metamorphosis in the Japanese flounder.

Lack of Skin Fibrosis in Tight Skin (TSK) Mice with Targeted Mutation in the Interleukin-4Rα and Transforming Growth Factor-β Genes

Scleroderma is a disorder characterized by fibrosis of the skin and internal organs and autoimmunity. Whereas the cause is unknown, interleukin-4 and transforming growth factor-beta have been postulated to play a major part in the fibrosis. To investigate the part played by these cytokines, we prepared TSK/+ mice with a targeted mutation in the interleukin-4R alpha or transforming growth factor-beta genes. The breeding failed to produce TSK/+ transforming growth factor-beta -/- mice so analysis of the role of transforming growth factor-beta was limited to TSK/+ transforming growth factor-beta +/- mice. We observed that TSK/+ interleukin-4R alpha -/- did not develop dermal thickening, and deletion of one allele of the transforming growth factor-beta gene resulted in diminished dermal thickness compared with TSK/+ mice; however, the deletion of interleukin-4R alpha or transforming growth factor-beta had no effect on lung emphysema, which is another characteristic of TSK syndrome. Electron microscopic analysis of skin showed that the collagen fibrils in TSK/+ interleukin-4R alpha -/- mice exhibit normal periodicity but have a smaller diameter than the fibers found in C57BL/6 mice. Analysis of skin and serum samples showed that the deletion of interleukin-4R alpha or one allele of transforming growth factor-beta prevented the increase of skin thickness paralleled with a decrease in the dermal hydroxyproline content and development of autoantibodies associated with TSK syndrome. These results demonstrate the importance of interleukin-4 and transforming growth factor-beta for the development of cutaneous fibrosis in vivo and suggest an important part for these cytokines in wound healing and connective tissue maintenance in general.

Qualidade de bulbos de cebola em consequência de tratamentos pré-colheita

Com o objetivo de se avaliar o efeito de tratamentos pré-colheita na qualidade de bulbos de cebola, através dos parâmetros perda de peso, espessura e coloração da casca, diâmetro e firmeza do bulbo, foi conduzido experimento em Paulínia, Estado de São Paulo, em 1997. Foram utilizados quatro tratamentos: testemunha; oxicloreto de cobre (250 g 100 L-1 de água); ácido bórico (250 g 100 L-1 de água); e a combinação dos dois últimos e seis cultivares: Serrana, Régia, Crioula e três híbridos da SVS, HT, HS-1 e HS-2. Os tratamentos foram aplicados durante a bulbificação. Os bulbos foram armazenados à temperatura ambiente (25ºC) e analisados periodicamente para os parâmetros citados. Os resultados permitiram observar que a aplicação pré-colheita do oxicloreto de cobre, nas quatro últimas semanas do ciclo, aumentou significativamente a resistência da casca dos bulbos, reduziu a perda de peso e incrementou a coloração dos mesmos, para todas as cultivares. Cultivares com casca mais escura apresentaram melhor resposta aos tratamentos pré-colheita para a coloração, do que as de casca mais clara. A firmeza dos bulbos, não foi influenciada pelos tratamentos pré-colheita.

In vivo study of skin mechanical properties in psoriasis vulgaris.

The aim of this study was to investigate the mechanical properties of the skin in psoriatic plaques before and after treatment with dithranol and in clinically uninvolved psoriatic skin in comparison with the skin of healthy controls. In total, 82 psoriatic plaques in 19 in-patients and 51 age-matched control subjects were studied with a non-invasive suction device (Cutometer). The plaques were characterized by statistically significant lower skin distensibility and elasticity, and a higher viscoelastic to elastic ratio compared with adjacent apparently normal skin. Delayed distension and hysteresis measured using a 2-mm diameter probe were decreased, but were increased when measured by a 8-mm diameter probe. These differences can be explained by the increased skin thickness in psoriasis and by the different aspects of skin mechanics determined by the 2 measuring probes. After treatment, the mechanical parameters of psoriatic plaques approached the values of adjacent control skin. The uninvolved volar forearm skin in psoriatic patients (2-mm diameter probe) showed statistically significant lower values of skin distensibility and higher values of viscoelasticity parameters compared with the skin of healthy control subjects. This suggests that the normal-appearing psoriatic skin is not entirely normal. The non-invasive method applied can be used for objective and quantitative evaluation of the effect of therapy in patients with psoriasis.

Regional variations in pain to controlled mechanical skin traumas from automatic needle insertions and relations to ultrasonography

Background/aims: Variations in pain from needle insertions in different anatomical regions have not previously been investigated in relation to the mechanical parameters of needle insertions. The objective of the present study was to investigate these relations and furthermore to investigate possible relations between the skin parameters measured by high‐frequency ultrasound and the mechanical parameters of needle insertion.Methods: Forty‐eight needle insertions were performed in a randomised and blinded design into the deltoid region, the abdominal region, and the lateral region of the thigh in 30 healthy volunteers. The insertions were performed with hypodermic insulin needles 27 gauge (G) and 30G, at 19 mm/s, 90 degree angle, and 8 mm along the insertion axis. From each needle insertion the occurrence, intensity, and quality of pain as well as bleeding, and mechanical insertion parameters [maximum mechanical needle penetration force (N), indentation work load (10‐3 Nm), and total mechanical work load (10‐3 Nm)] were registered. Also, the skin of each anatomical region was characterised by 20‐MHz ultrasonographic examination.Results: The maximum mechanical penetration force was highest in the thigh and lowest in abdominal region (P<0.01). The indentation work load was lowest in the thigh (P<0.001). The total mechanical work load was highest in the deltoid region and lowest in the abdominal region (P<0.001). The occurrence of bleeding from the needle insertions was lowest in the abdominal region (P=0.01). The occurrence of pain and the pain quality from needle insertions did not differ between the anatomical regions. However, the intensity of pain in the needle insertions reported to be painful was lowest in the deltoid region (P<0.01). Positive relations between higher mechanical parameters of insertions with 30G needles and the occurrence of pain were demonstrated. Higher total mechanical work load was related to increased pain intensity. Ultrasonographically, the thickness of the epidermal entrance echo was highest in the thigh (P<0.001), and the thickness of both the dermal echo and the total skin echo thickness were highest in the abdominal region (P<0.001). The mean ultrasonographic density of the dermal echo was lowest in the abdominal region and highest in the thigh (P<0.001). The thickness of the dermal echo, of the total skin echo and the dermal echo density were all significantly inversely related to the indentation work load (P<0.001).Conclusions: Specific mechanical parameters of needle insertions could be demonstrated in different anatomical regions. Differences in pain perception from needle insertions in different anatomical regions were not reflected by occurrence of pain but by pain intensity, with the lowest pain intensity registered in the deltoid region. Ultrasonographically, increased skin thickness and decreased density of the dermal echo were related to lower indentation work load during the needle insertions.

Formation of integral skin polyurethane foams

AbstractPolyurethane integral skin foams comprise a low density foamed core surrounded by a high density skin of the same material, and are made in a single molding operation. Polyurethane integral skin foams find wide application as structural materials, and the mechanical properties of such foams are significantly affected by the foam structure, which in turn is determined by the foaming process. An experimental and theoretical study of the foam formation process is presented. Experimental results show that increase in the mold wall temperature results in an increase in the upper skin thickness, a decrease in the lower skin thickness, and a decrease in the density of both skins. The core density increases with increasing wall temperature. Increase in the blowing agent concentration produces a small increase in the skin thickness. Computations based on the model of Marciano et al. [Polym. Eng. Sci., 26, 717 (1986)] are presented using an efficient numerical technique. Predictions of the model for the skin thickness, core density and pressure and temperature variation with time are in reasonable agreement with experimental data. The model, however, predicts higher skin densities than the experimental measurements. A modification of the initial condition of the model to account for the air bubbles dispersed during mixing gives better agreement between theory and experiment.

Increased reduction in bone density and skin thickness in postmenopausal women taking long-term corticosteroid therapy: a suggested role for estrogen add-back therapy

Background Long-term corticosteroid therapy is complicated by osteoporosis and generalized thinning of the skin. These two complications of such therapy were routinely assessed at the Menopause Clinic of St. Luke's Hospital Medical School, University of Malta.Methods A cross-sectional study was performed on 64 postmenopausal women who had been taking long-term corticosteroids. Each woman had her skin thickness measured using high-resolution ultrasound (22 MHz) and her bone density measured by dualenergy X-ray absorptiometry (DEXA). These measurements were compared with those of a control group (n = 557), a group of women who had sustained osteoporotic fractures (n = 180) and a group of women taking hormone replacement therapy (HRT) (n = 399). A longitudinal study of 29 postmenopausal women taking corticosteroids was also performed. This study compared results for women who, in addition to their corticosteroids, were taking HRT and for those who were taking corticosteroids alone.Results The cross-sectional study showed that corticosteroid therapy was associated with the lowest mean skin thickness measurement (0.83 mm). Similarly, low mean bone density measurements for the lumbar spine (0.805 g/cm2) and left hip (0.715 g/cm2) were obtained for this group.The mean skin thicknesses in the control group and the HRT group were 0.93 mm and 0.935 mm, respectively, while that in the osteoporotic fracture group was 0.88 mm. The bone density of the fracture group was similar to that of the group of women taking long-term corticosteroids, with the lumbar spine having a mean density of 0.805 g/cm2 and 0.81 g/cm2, and the left hip having a density of 0.705 g/cm2 and 0.715 g/cm2, respectively. Bone densities were similar for the control group and the HRT group, and higher than that of the corticosteroid or fracture group. The lumbar spine had a mean density of 0.925 g/cm2 in the control group and 0.93 g/cm2 in the hormonally treated group. Both the treated and control groups had similar bone densities of the left hip at about 0.82 g/cm2.The small longitudinal study compared postmenopausal women on long-term corticosteroid therapy taking HRT with another group who were not taking HRT. This 4-year study revealed mean total increases in skin thickness of 6.1% and bone density of 5.5% (left hip) and 14.6% (lumbar spine) in the HRT group, since the start of the study. Conversely, the control group registered reductions over 4 years in both skin thickness (2.8%) and bone density (lumbar spine 4.5% and hip 5.0%).Conclusion In postmenopausal women taking long-term corticosteroids, skin thickness and bone density were both decreased, but the addition of HRT as add-back improved the situation dramatically. Skin thickness and bone density in women taking long-term corticosteroids were comparable to those in women who had sustained osteoporotic fractures. It is therefore suggested that HRT be used as add-back therapy in postmenopausal women taking long-term corticosteroid therapy.

Delayed type hypersensitivity theilerin test in cattle vaccinated against Theileria annulata infection

Theilerin was prepared and its total nitrogen was determined at level of 1 mg/ml. Seventy-two Holstein Friesian cattle recovered from acute theileriosis or vaccinated received 0.1 ml of theilerin intradermally at normal concentration of total nitrogen or other dilutions (1/10 and 1/100). Some 60% of calves and 66.67% of milking cows receiving normal theilerin showed more than 1 mm increase in skin thickness at the site of inoculation (mean value of 1.86 mm for calves and 3.46 mm for milking cows). The pathological examination of the inoculation site showed infiltration of lymphocytes. No changes of general condition were observed in animals under study. The result indicated that the test is positive and could be used for checking Immunity in vaccinated animals.

Morphological classification of nuchal skin in human fetuses with trisomy 21, 18, and 13 at 12-18 weeks and in a trisomy 16 mouse.

An increase in the nuchal translucency that can be detected at 10-14 weeks of gestation by ultrasound forms the basis for a screening test for chromosomal abnormality. Several mechanisms leading to this increase in skin thickness have been proposed, including changes of the extracellular matrix, cardiac defects and abnormalities of the large vessels. This study examines the composition of the extracellular matrix of the skin in gestational age-matched fetuses with trisomy 21, 18 and 13 from 12-18 weeks. Immunohistochemistry was applied with monoclonal and polyclonal antibodies against collagen type I, III, IV, V and VI and against laminin and fibronectin. Collagen type VI gene expression was further studied by in situ hybridization to detect differences in expression patterns of COL6A1, COL6A3 and COL1A1 between normal fetuses and those with trisomy 21. The ultrastructure of tissue samples was studied by transmission electron microscopy (TEM) and additionally by immunogold TEM. Further, we examined the morphology of the skin in an animal model for Down's syndrome, the murine trisomy 16, by light and TEM. The dermis of trisomy 21 fetuses was richer in collagen type VI than that of normal fetuses and other trisomies, and COL6A1, located on chromosome 21, was expressed in a wider area than COL6A3, which is located on chromosome 2. Collagen type I was less abundant in the skin of trisomy 18 fetuses, while the skin of all three trisomies contained a dense network of collagen type III and V in comparison with normal fetuses. Collagen type IV, of which two genes are located on chromosome 13, was expressed in the basement membranes of the skin in all fetuses and additionally in the dermal fibroblasts only of trisomy 13 fetuses. Likewise, laminin was present in all basement membranes of normal and trisomic fetuses as well as in dermal fibroblasts of fetuses with trisomy 18. LAMA1 and LAMA3 genes are located on chromosome 18. Dermal cysts were found in the skin of trisomy 18 and 13, but not in trisomy 21 and normal fetuses. Ultrastructural findings showed that an extracellular precipitate containing glycosaminoglycans was regularly present in the skin of trisomy 21 fetuses and murine trisomy 16 embryos. In conclusion, this study suggests that the skin edema in fetal trisomies is characterized by specific alterations of the extracellular matrix that may be attributed to gene dosage effects as a result of a genetic imbalance due to the condition of fetal trisomy.

Cutaneous microdialysis in the rat: insertion trauma studied by ultrasound imaging.

Microdialysis is a method by which compounds can be studied in the extracellular space in skin, in vivo. The microdialysis probe is inserted in the dermis using a guide cannula. It is expected that intradermal oedema associated with insertion trauma as well as the probe depth can influence the results of microdialysis studies. The aim of the present study was to assess the effects of insertion trauma and, additionally, the probe depth by ultrasound. High-frequency (20 MHz) ultrasound is a noninvasive method for measuring the thickness and echostructure of skin. Hairless rats were anaesthetized with either halothane (n = 7) or pentobarbital sodium (n = 6). The insertion of the microdialysis probe resulted in a 38% relative increase in skin thickness. At 120 min the skin thickness had not reached the pre-insertion value. Thus, significant skin thickening, representing traumatic oedema, developed due to insertion of the microdialysis probe in the skin. The microdialysis probe could be inserted reproducibly in the lower dermis.

Effects of α-hydroxy acids on photoaged skin: Apilot clinical, histologic, and ultrastructural study

alpha-Hydroxy acids (AHAs) have been reported to improve aging skin. The mechanisms of action of AHAs on epidermal and dermal compartments need clarification. Our purpose was to determine the effects of AHAs on photoaged human skin by clinical and microanalytic means. Patients applied a lotion containing 25% glycolic, lactic, or citric acid to one forearm and a placebo lotion to the opposite forearm for an average of 6 months. Thickness of forearm skin was measured throughout the study. Biopsy specimens from both forearms were processed for analysis at the end of the study. Treatment with AHAs caused an approximate 25% increase in skin thickness. The epidermis was thicker and papillary dermal changes included increased thickness, increased acid mucopolysaccharides, improved quality of elastic fibers, and increased density of collagen. No inflammation was evident. Treatment with AHAs produced significant reversal of epidermal and dermal markers of photoaging.

Immunohistological study of the cutaneous delayed type hypersensitivity reaction in sheep

The cutaneous delayed type hypersensitivity (DTH) reaction may be experimentally initiated both as an in-vivo technique for the study of the cell mediated arm of the immune system, and also as an accurate clinical test of the functional capacity of this part of the immune response. This study was performed to fully evaluate the immunohistological characteristics of the normal DTH reaction utilising an ovine model. Six clinically healthy sheep were inoculated with an intradermal Mycobacterium bovis vaccine. After 21 days, they were challenged with multiple intradermal injections of a purified protein derivative (PPD) of M. bovis in the hairless skin of the medial thigh. Simultaneous contralateral injections of sterile diluent were performed to provide control material. The resulting lesions were measured for increase in skin thickness and biopsied at 2, 7, 24, 48, 72, and 96 h post injection. The biopsies were divided, and stained both histochemically and with monoclonal antibodies directed against lymphocyte subsets, macrophages, and B cells. The DTH reaction was maximal at 72 hours post challenge, and was largely characterised by an initial influx of polymorphonuclear neutrophil (PMN) cells, after which there was an accumulation of αβ T cells. The number of macrophages within the lesion declined with the progression of the reaction. B cells and γδ T cells did not appear to play a major role in the response. Fibrin was a marked component of the reaction at later time points.

The specificity of the single cervical intradermal tuberculosis test in a population of Tasmanian fallow deer putatively free of bovine tuberculosis

The single cervical intradermal tuberculin test was used on 34 farmed fallow deer in Tasmania, to determine the specificity of this test when increases in skin thickness of 1 and 2 mm were used as arbitrary significant responses. This was to assess the response that could be expected if this test was used in monitoring or export testing programs of deer in Tasmania. Tasmania is free from bovine tuberculosis, thus providing a unique opportunity to undertake such a study. All deer were slaughtered following testing, and thoroughly inspected post-mortem. Deer that reacted to the skin test had lymph nodes cultured for the presence of Mycobacteria sp. With the reactor response set at 1 mm or more, 25 out of 34 deer tested did not react to the skin test, giving a specificity of 73.5% (95% CI 57.5–89.5%). With the reactor response set at 2 mm or greater, the specificity of the test was 100%. One lymph node each from two reactors contained mycobacteria identified as Mycoplasma avium and Mycoplasma scrofulaceum. This trial indicates that despite being free of bovine tuberculosis for 20 years, Tasmania also experiences the same difficulties as other countries in the use of the single cervical skin test for certifying deer free from bovine tuberculosis.

Ultrasound measurement of skin thickness in systemic sclerosis.

Sclerotic skin change in systemic sclerosis (SSc) usually accompanies increased skin thickness. In order to quantify the cutaneous changes and to clarify the changes in the 'uninvolved' skin in systemic sclerosis (SSc), we measured the skin thickness on the chest, the forearms and the hands of 79 patients with SSc and 81 healthy controls with a B-mode ultrasound (30 MHz) apparatus. The thickness of the 'uninvolved', as well as the 'involved' skin in patients with SSc was significantly greater than that of healthy controls. Increased skin thickness on the forearms and/or the hands showed a 64.6% sensitivity and a 100% specificity for SSc. These results indicated that the skin which appears to be 'uninvolved' in patients with SSc is already pathologic, as shown by increased thickness. Moreover, measurement of skin thickness may be beneficial in the diagnosis of this disease at an early stage.

Echographic diagnosis of pretibial myxedema in patients with autoimmune thyroid disease

In the present study we have evaluated the use of pretibial ultrasound for the diagnosis of pretibial myxedema (PTM). We studied 76 patients, 58 with Graves' disease, 13 with Hashimoto's thyroiditis and five with idiopathic hypothyroidism. Thirty-two normal subjects were also studied as controls. Sixty-four patients had associated ophthalmopathy. The ultrasound scanner was equipped with 10- and 13-MHz probes. Punch biopsies were carried out in 11 patients and tissue sections examined on a light microscope. On clinical examination 21 patients (28%) had suspected PTM. By ultrasound, we measured the thickness of dermis and subcutaneous tissue (D1) and that including only deeper dermis (D2) in normal subjects to define the echographic parameters of normal pretibial skin. We then found increased skin thickness in 25 patients (33%), with mean D1 and D2 values significantly higher than those measured in controls (p < 0.00001). The echographic study was positive in 20 patients with ophthalmopathy (31%). Ultrasound showed increased skin thickness in 16 of 21 patients (76%) with clinically suspected PTM. Histopathological findings confirmed the presence of PTM in all the patients who underwent pretibial skin biopsy. We believe that the measurement of pretibial skin thickness by ultrasound may be useful for revealing the presence of PTM.

Skin Thickness in Expanded Human Breast Skin

By means of an ultrasonic technique, skin thickness was measured in 13 women subjected to mammary reconstruction by tissue expansion. Measurements were performed the day before introduction of the expander, after the last inflation, the day before introduction of the permanent implant, and at 2 weeks and 6 months after this operation. Five patients had their expanders inflated every day (rapid expansion), and 8 patients, once a week (slow expansion). A decrease in skin thickness during the inflation period was recorded, and this decrease was permanent even 6 months after the second operation. After exchange of the expander for a permanent implant, there was a transient statistically significant increase in skin thickness. There was no statistical difference between the groups of rapid and slow expansion.

Comparison of the Effects of Calcipotriol, Prednicarbate and Clobetasol 17-Propionate on Normal Skin Assessed by Ultrasound Measurement of Skin Thickness

In this study, we investigated the effect of calcipotriol, prednicarbate and clobetasol 17-propionate on skin thickness over a treatment period of 6 weeks. The study was conducted as a controlled, randomized, double-blind comparison. The influence of these drugs on normal skin under occlusive conditions was assessed visually and by measuring skin thickness using 20 MHz B mode ultrasound. Both topically applied glucocorticosteroids lead to a significant decrease in skin thickness. In contrast to the glucocorticosteroid-induced atrophy, calcipotriol application on normal skin leads to an increase in skin thickness in all volunteers. The effect remains constant for the duration of treatment. The cause of this increase seems to be an irritative reaction of the skin which was histologically investigated in one volunteer. The histological features of this reaction are characteristic for a subacute dermatitis. The implications of these findings for the therapeutic mechanism of calcipotriol are discussed.

Effect of antiinsulin-like growth factor 1 on epidermal proliferation of human skin transplanted onto nude mice treated with growth hormone

Recently it has been demonstrated that long-term administration of GH leads to increase of skin thickness. The aim of the present study was to determine whether this effect of GH is mediated by insulin growth factor 1 (IGF-1), which enhances epidermal proliferation. In order to address this question, human split-thickness grafts obtained from aged skin were grafted onto nude mice. One group of mice was treated systemically with GH, whereas a second group was treated with intradermal graft injections of anti-IGF-1 in addition to GH. A third group received distilled water and served as a control group. Histological and autoradiographic analyses were performed before and after engraftment. The GH-treated mice showed a significant increase in epidermal proliferation measured by epidermal thickness (analysis of variance with repeated measurements, P < 0.01) and labeled index (analysis of variance, P < 0.01) as compared to the control group. The intradermal injections of anti-IGF-1 reduced significantly the proliferative stimulatory effect of GH (P < 0.01). The present study emphasizes the role of IGF-1 in the increased skin thickness observed after GH administration and provides a useful model for determining the effect of various compounds, including GH, on human skin.

An evaluation of the comparative tuberculin skin test for detecting tuberculosis in farmed deer

A comparative cervical skin test using 1.0 mg/ml bovine purified protein derivative and 0.5 mg/ml avian purified protein derivative was evaluated as a method for detecting tuberculosis in farmed deer. A positive comparative cervical skin test reaction was defined as a bovine response with a 2 mm or greater increase in skin thickness which was greater or equal to the avian response. Estimates of the sensitivity of the comparative cervical skin test were obtained from a series of experiments conducted on 60 deer intratracheally inoculated with Mycobacterium bovis. Prior tuberculin skin testing was found to suppress the skin reactivity to a subsequent comparative cervical skin test. This effect was most pronounced at short intervals of 3-7 days, but could still be measured 60 days after the previous test. When the test interval was greater than 60 days, the sensitivity of the comparative cervical skin test was 91.4%. The specificity of the comparative cervical skin test was 98.7% when 1157 deer from 17 uninfected herds with a history of nonspecific skin test reactions were examined. There was no statistical difference in the mean skin thickness increases of three groups of infected animals tested with 2 mg/ml, 0.2 mg/ml and 0.02 mg/ml of bovine purified protein derivative respectively.