The Wellcome Foundation lecture, 1984. Nuclear magnetic resonance imaging in medicine: medical and biological applications and problems

From early biological work and the first T1 nuclear magnetic resonance (n.m.r.) animal image in 1974, whole-body patient images, by using a two-dimensional Fourier transform method were achieved in Aberdeen in 1980 with a 0.04 T vertical resistive magnet. Different pulse sequences produce images dependent by different amounts on proton density, T1 and T2, and for clinical work it is advantageous to use more than one pulse sequence to image pathology. The slow improvement of spatial resolution with increasing standing magnetic field strength is discussed and information on the T1 and T2 contrast dependence is reviewed: it suggests that the gains from high fields may be less than believed hitherto. Electrocardiogram gating can be used to produce moving images of the beating heart; blood flow can be imaged and surface radiofrequency coils are used for improved detail. N.m.r. imaging has considerable potential for studying response to therapy; mental states and dementia; tissue generation; discriminating body fat and body fluids. Other nuclei such as 23Na can be imaged and the potential to image fluorine-labelled pharmaceuticals could be very exciting; n.m.r. contrast agents are now being developed. Images formed from T1 values measured for each pixel are very useful for diagnosis, but the numerical values themselves are less valuable for distinctive pathological identification. With 15 companies manufacturing n.m.r. imagers and over 200 in use in hospitals, the technique is rapidly becoming established in diagnostic clinical practice and some typical uses are presented.     

Experimental protocol for tissue discrimination in vitro by n.m.r.

We have examined the n.m.r. relaxation times T1 and T2 of water protons for liver (mouse, human) and brain (mouse) at different temperatures and subjected to various conditions of conservation and degeneration. After tissue degeneration, T1 and T2 behave differently and their variations are characteristic of each tissue type. The results show that the initial values at +4 degrees C are consistent when the experimental protocol formulated in this study is followed.     

Gender differences in regional body composition and somatotrophic influences of IGF-I and leptin.

This study evaluated the arm, trunk, and leg for fat mass, lean soft tissue mass, and bone mineral content (BMC) assessed via dual-energy X-ray absorptiometry in a group of age-matched (approximately 29 yr) men (n = 57) and women (n = 63) and determined their relationship to insulin-like growth factor I (IGF-I) and leptin. After analysis of covariance adjustment to control for differences in body mass between genders, the differences that persisted (P < or = 0.05) were for lean soft tissue mass of the arm (men: 7.1 kg vs. women: 6.4 kg) and fat mass of the leg (men: 5.3 kg vs. women: 6.8 kg). Men and women had similar (P > or = 0.05) values for fat mass of the arms and trunk and lean soft tissue mass of the legs and trunk. Serum IGF-I and insulin-like growth factor binding protein-3 correlated (P < or = 0.05) with all measures of BMC (r values ranged from 0.31 to 0.39) and some measures of lean soft tissue mass for women (r = 0.30) but not men. Leptin correlated (P < or = 0.05) similarly for measures of fat mass for both genders (r values ranging from 0.74 to 0.85) and for lean soft tissue mass of the trunk (r = 0.40) and total body (r = 0.32) for men and for the arms in women (r = 0.56). These data demonstrate that 1) the main phenotypic gender differences in body composition are that men have more of their muscle mass in their arms and women have more of their fat mass in their legs and 2) gender differences exist in the relationship between somatotrophic hormones and lean soft tissue mass.     

The Wellcome Foundation lecture, 1981. Nuclear magnetic resonance imaging in medicine: physical principles

In recent years nuclear magnetic resonance (n.m.r.) has become a means of providing excellent images of the interior of the human body which are proving useful in medical practice. The development of n.m.r. imaging, much of which was pioneered in Britain, is outlined. Proton image resolution of human anatomy is comparable with X-ray computed tomography images, but without the hazard of ionizing radiation. There is improved soft tissue discrimination and pathological contrast through the basic imaging parameters of the proton density and the relaxation times T1 and T2, whose differences from one tissue to another are exploited by use of appropriate radiofrequency pulse sequences. Images may be obtained directly of transverse, coronal and sagittal sections of the head and body. Single slices or multiple slices may be imaged and imaging may be done in three dimensions. The lecture describes the more important imaging techniques and gives illustrative examples of images obtained. The efficient use of time in n.m.r. imaging is discussed, particularly mentioning the multiecho-multislice procedure and the development of real-time n.m.r. imaging. Magnetic field strengths in current use for proton n.m.r. imaging range from 0.02 to 2 T. At the lower end of the range resistive magnets are used, while for higher fields superconducting magnets are needed. A considerable improvement in image quality is obtained by use of special receiver coils.     

Differences in adiponectin protein expression: effect of fat depots and type 2 diabetic status.

Adiponectin is an adipocyte-derived hormone associated with insulin sensitivity and atherosclerotic risk. As central rather than gluteofemoral fat is known to increase the risk of type 2 diabetes and cardiovascular disease, we investigated the mRNA and protein expression of adiponectin in human adipose tissue depots. RNA was extracted from 46 human adipose tissue samples from non-diabetic subjects aged 44.33 +/- 12.4 with a BMI of 28.3 +/- 6.0 (mean +/- SD). The samples were as follows: 21 abdominal subcutaneous, 13 omentum, 6 thigh; samples were also taken from diabetic subjects aged 66.6 +/- 7.5 with BMI 28.9 +/- 3.17; samples were: 6 abdominal subcutaneous; 3 thigh. Quantitative PCR and Western analysis was used to determine adiponectin content. Protein content studies determined that when compared with non-diabetic abdominal subcutaneous adipose tissue (Abd Sc AT) (values expressed as percentage relative to Abd Sc AT -100 %). Adiponectin protein content was significantly lower in non-diabetic omental AT (25 +/- 1.6 %; p < 0.0001, n = 6) and in Abd Sc AT from diabetic subjects (36 +/- 1.5 %; p < 0.0001, n = 4). In contrast, gluteal fat maintained high adiponectin protein content from non-diabetic patients compared with diabetic patients. An increase in BMI was associated with lower adiponectin protein content in obese ND Abd Sc AT (25 +/- 0.4 %; p < 0.0001). These findings were in agreement with the mRNA expression data. In summary, this study indicates that adiponectin protein content in non-diabetic subjects remains high in abdominal subcutaneous fat, including gluteal fat, explaining the high serum adiponectin levels in these subjects. Omental fat, however, expresses little adiponectin. Furthermore, abdominal and gluteal subcutaneous fat appears to express significantly less adiponectin once diabetic status is reached. In conclusion, the adipose tissue depot-specific expression of adiponectin may influence the pattern of serum adiponectin concentrations and subsequent disease risk.     

N.m.r. imaging of intact biological systems

Internal images of structured objects may be obtained with n.m.r. by labelling component parts with different magnetic field strengths and therefore recognizably different n.m.r. frequencies. A linear field gradient generates a one-dimensional projection of nuclear density and a variety of techniques are employed to manipulate this one-dimensional probe to yield internal images in two and three dimensions. In the past few years, n.m.r. imaging, sometimes also called zeugmatography or spin mapping, has been applied progressively to provide proton images of small phantoms, fruit, vegetables and small animals, and finally to in vivo imaging of the human body; it promises to provide a valuable means of interior investigation of intact biological systems generally. For medical imaging the method is non-invasive, does not use ionizing radiations, appears to be without hazard and penetrates bony cavities without attenuation. Furthermore, other n.m.r. parameters, for example, relaxation times and fluid flow, may also be mapped; there is evidence that the relaxation times from tumours are significantly longer than those from corresponding normal tissue. Effort to date has mostly been concentrated on proton n.m.r., but some work has been done with other nuclei. Three examples are shown of n.m.r. images of intact biological systems: a fruit, an animal and a human system. The discussion includes the quantitative nature of the images, tissue discrimination, the relation between the resolution in the image and image acquisition time, attenuation and phase shift of the r.f. field in the biological tissue, and magnets suitable for n.m.r. imaging. In principle, all conventional n.m.r. techniques can be combined with n.m.r. methods in order to investigate heterogeneous systems. Overhauser imaging is briefly discussed.     

Matrix metalloproteinases, tissue inhibitors of metalloproteinases, aminoterminal propeptide of procollagen type III, and hyaluronan in sera and tissue of patients with capsular contracture after augmentation with Trilucent breast implants

In various fibrotic diseases, matrix metalloproteinases (MMPs) and their natural inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), play an important role. In our study, serum concentrations of MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were determined by enzyme-linked immunosorbent assay in 17 female patients with Baker grade II (n =9), III (n =7), and IV (n =1) capsular contracture after bilateral cosmetic mamma augmentation with Trilucent implants (AEI, Inc., Caversham, United Kingdom). Samples of capsular tissue for standard histology and immunohistochemistry were obtained from all patients. Sera from 20 female patients who had plastic surgery for reduction mammaplasty were used as the control group. The aminoterminal propeptide of procollagen type III (PIIINP) and hyaluronan were analyzed as markers for fibrogenesis in both groups, too. Statistical analysis was performed using the Mann-Whitney test and Spearman rank correlation. Patients with capsular contracture presented significantly higher concentrations of TIMP-1 and TIMP-2 in their sera than did the control group (p < 0.05), which correlated with Baker grade (r = 0.7 versus r = 0.65; p < 0.05). The concentration of MMP-2 was significantly higher in the sera of patients with capsule fibrosis, whereas there were no significant differences in MMP-1, MMP-9, and PIIINP serum concentrations. Patients with capsule fibrosis had a significantly lower MMP-to-TIMP ratio (1.1 +/- 0.4, p <0.05) than the control group (1.5 +/- 0.4), which correlated with the Baker classification (r =0.7; p <0.05). The hyaluronan serum concentration of patients with capsular contracture was significantly higher (p < 0.05) and correlated with the Baker grade (r = 0.73; p < 0.05), whereas PIIINP showed no difference. In the histologic evaluation, there was a chronic inflammatory reaction in the capsules around the breast implants and refracting material within the substance. Immunohistochemically, TIMP-1 and TIMP-2 showed an intensive accumulation, and MMP-2 showed a local reaction. PIIINP could be detected, too, whereas there was no staining for MMP-1 and MMP-9.The elevated systemic MMP-2 concentration and the local positive staining in the tissue might be due to the chronic inflammatory reaction. Nevertheless, the balance between MMPs and their natural inhibitors is disturbed in patients with capsule contracture. The elevated systemic concentration of TIMPs might be a pathway in the pathogenesis of severe fibrosis after breast augmentation with alloplastic material. Hyaluronan might be a useful marker for early prediction of capsule fibrosis, whereas PIIINP is not useful as a predictor.     

Gender specific correlations of adrenal gland size and body fat distribution: a whole body MRI study.

OBJECTIVE: The aim of this study was to investigate the gender specific correlations of stress related tissues [adrenal gland volume (AV), visceral fat] and alimentary dependent fat compartments with cortisol concentrations in healthy male and female subjects. METHODS: Fourteen men and 13 women were examined. Fat compartments [whole body fat, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SCAT)] were determined using whole body MRI. Adrenal gland volume was assessed by a 3D MR data set. The salivary cortisol was determined at 9 AM and 4 PM. RESULTS: Men had significantly more visceral fat and less subcutaneous fat than women. Adrenal gland size correlated significantly with the visceral and subcutaneous fat in women (r=0.7, p=0.008), but not in men (r=0.2, p=0.4). There was a negative correlation between the decrease of cortisol between 9 AM and 4 PM with VAT (r=-0.451, p=0.027) in the whole group. DISCUSSION: The high correlation between the adrenal gland volume and VAT in women underlines the link between hypothalamic-pituitary-adrenal (HPA) axis, stress, and circadian cortisol rhythm, respectively, and an increased abdominal fat volume. The lack of correlation between visceral fat and adrenal volume in men points to an additional influence of sex hormones.     

Adipose tissue distribution in relation to insulin resistance in type 2 diabetes mellitus

Insulin resistance (IR) is typically more severe in obese individuals with type 2 diabetes (T2DM) than in similarly obese non-diabetics but whether there are group differences in body composition and whether such differences contribute to the more severe IR of T2DM is uncertain. DEXA and regional CT imaging were conducted to assess adipose tissue (AT) distribution and fat content in liver and muscle in 67 participants with T2DM (F39/M28, age 60 +/- 7 yr, BMI 34 +/- 3 kg/m(2)) and in 35 similarly obese, non-DM volunteers (F20/M15, age 55 +/- 8 yr, BMI 33 +/- 2 kg/m(2)). A biopsy of subcutaneous abdominal AT was done to measure adipocyte size. A glucose clamp was performed at an insulin infusion of 80 mU x min(-1) x m(-2). There was more severe IR in T2DM (6.1 +/- 2.3 vs. 9.9 +/- 3.3 mg x min(-1) x kg FFM(-1); P < 0.01). Group comparisons of body composition parameters was performed after adjusting for the effect of age, gender, race, height and total fat mass (FM). T2DM was associated with less leg FM (-1.2 +/- 0.4 kg, P < 0.01), more trunk FM (+1.1 +/- 0.4 kg, P < 0.05), greater hepatic fat (P < 0.05), and more subfascial adipose tissue around skeletal muscle (P < 0.05). There was a significant group x sex interaction for VAT (P < 0.01), with greater VAT in women with T2DM (P < 0.01). Mean adipocyte size (AS) did not significantly differ across groups, and smaller AS was associated with increased leg FM, whereas larger AS was related to more trunk FM (both P < 0.05). Group differences in IR were less after adjusting for group differences in leg FM, trunk FM, and hepatic fat, but these adjustments only partially accounted for the greater severity of IR in T2DM. In summary, T2DM, compared with similarly obese nondiabetic men and women, is associated with less leg FM and greater trunk FM and hepatic fat.     

Effects of the G-protein beta3 subunit 825T allele on adipogenesis and lipolysis in cultured human preadipocytes and adipocytes.

The recently discovered C825T polymorphism of the G-protein beta 3 subunit has been reported to be associated with the development of hypertension and obesity. The aim of our study was to investigate the relationship between the C825T polymorphism and functional aspects of human adipose cells, particularly with regard to adipose differentiation and lipolysis. Adipose tissue samples were collected from 65 women with a BMI ranging from 19.7 to 39.7 kg/m 2 undergoing surgical mammary reduction. The stromal cells were allowed to undergo differentiation in primary culture using adipogenic media of defined composition. No significant difference was observed between the CC carriers and the carriers of the T allele under all adipogenic conditions with differentiation capacity related to the genotype. In a subgroup of patients (n = 20), lipolysis in isolated fat cells was determined by measurement of glycerol in the culture medium upon catecholamine exposure. Glycerol release after 10(-7) mmol/l isoproterenol was significantly higher in fat cells from the 10 CC carriers than in adipocytes from the T allele carriers when expressed as percentage of basal glycerol release (increase above baseline: CC: 809 +/- 174 %, T allele carriers: 247 +/- 88 %, p = 0.01), while basal glycerol concentrations were no different according to genotype after controlling for either age or BMI. In conclusion, this study provides the first evidence that the GNB3 825T allele is associated with an impairment of the beta-adrenergic control of lipolysis.     

Depot-specific regulation of glucose uptake and insulin sensitivity in HIV-lipodystrophy

Altered fat distribution is associated with insulin resistance in HIV, but little is known about regional glucose metabolism in fat and muscle depots in this patient population. The aim of the present study was to quantify regional fat, muscle, and whole body glucose disposal in HIV-infected men with lipoatrophy. Whole body glucose disposal was determined by hyperinsulinemic clamp technique (80 mU x m(-2) x min(-1)) in 6 HIV-infected men and 5 age/weight-matched healthy volunteers. Regional glucose uptake in muscle and subcutaneous (SAT) and visceral adipose tissue (VAT) was quantified in fasting and insulin-stimulated states using 2-deoxy-[18F]fluoro-D-glucose positron emission tomography. HIV-infected subjects with lipoatrophy had significantly increased glucose uptake into SAT (3.8 +/- 0.4 vs. 2.3 +/- 0.5 micromol x kg tissue(-1) x min(-1), P < 0.05) in the fasted state. Glucose uptake into VAT did not differ between groups. VAT area was inversely related with whole body glucose disposal, insulin sensitivity, and muscle glucose uptake during insulin stimulation. VAT area was highly predictive of whole body glucose disposal (r2 = 0.94, P < 0.0001). This may be mediated by adiponectin, which was significantly associated with VAT area (r = -0.75, P = 0.008), and whole body glucose disposal (r = 0.80, P = 0.003). This is the first study to directly demonstrate increased glucose uptake in subcutaneous fat of lipoatrophic patients, which may partially compensate for loss of SAT. Furthermore, we demonstrate a clear relationship between VAT and glucose metabolism in multiple fat and muscle depots, suggesting the critical importance of this depot in the regulation of glucose and highlighting the significant potential role of adiponectin in this process.     

Insulin resistance and type 2 diabetes are not related to resistin expression in human fat cells or skeletal muscle.

Resistin is secreted by rodent fat cells and was recently postulated to be an important link between obesity and insulin resistance. We examined Resistin gene expression with real-time RT-PCR in human isolated fat cells, adipose tissue, and muscle from 42 individuals of varying degrees of overweight and who had normal insulin sensitivity or were insulin-resistant or Type 2 diabetic. Resistin was not expressed in human muscle nor was it expressed in most human isolated fat cells or intact biopsies. No difference was found between normal, insulin-resistant, or Type 2 diabetic samples. However, a very low but specific Resistin expression could be demonstrated in isolated fat cells and intact adipose tissue from some individuals (n = 3 and n = 4, respectively). There was no evidence for the expression of splice variants in the human samples. Thus, Resistin does not seem to be an important link to insulin resistance and Type 2 diabetes in human.     

HPLC法测定杨梅叶中杨梅苷的含量

目的:建立HPLC法测定杨梅叶中杨梅苷含量的方法。方法:采用Diamonsil C18(150 mm×4.6 mm,5μm)柱,流动相乙腈-0.1%磷酸水溶液梯度洗脱,流速1.0 mL/min,检测波长358 nm,柱温30℃。结果:杨梅苷在0.088-0.880 mg/mL内与峰面积呈良好线性关系,A=36113C-401.56,r=0.9994;平均回收率为102.4%,RSD=1.9%(n=9)。测得杨梅叶中杨梅苷含量为1.43%。结论:该测定方法准确,可靠,对于杨梅的进一步开发利用具有重要的参考意义。     

Proton-nuclear-magnetic-resonance studies of serum, plasma and urine from fasting normal and diabetic subjects.

Resonances for the ketone bodies 3-D-hydroxybutyrate, acetone and acetoacetate are readily detected in serum, plasma and urine samples from fasting and diabetic subjects by 1H n.m.r. spectroscopy at 400 MHz. Besides the simultaneous observation of metabolites, the major advantage of n.m.r. is that little or no pretreatment of samples is required. N.m.r. determinations of 3-D-hydroxybutyrate, acetoacetate, lactate, valine and alanine were compared with determinations made with conventional assays at six 2-hourly intervals after insulin withdrawal from a diabetic subject. The n.m.r. results closely paralleled those of other assays although, by n.m.r., acetoacetate levels continued to rise rather than reaching a plateau 4h after insulin withdrawal. The 3-D-hydroxybutyrate/acetoacetate ratio in urine during withdrawal gradually increased to the value observed in plasma (3.0 +/- 0.2) as determined by n.m.r. The acetoacetate/acetone ratio in urine (17 +/- 6) was much higher than in plasma (2.5 +/- 0.7). Depletion of a mobile pool of fatty acids in plasma during fasting, as seen by n.m.r., paralleled that seen during insulin withdrawal. These fatty acids were thought to be largely in chylomicrons, acylglycerols and lipoproteins, and were grossly elevated in plasma samples from a non-insulin-dependent diabetic and in cases of known hyperlipidaemia.     

Tylenchorhynchus microconus n.sp., T. crassicaudatus leviterminalis n.subsp. and T. coffeae Siddiqi & Basir, 1959 (Nematoda: Tylenchida)

Summary Tylenchorhynchus microconus n.sp. from around roots of Australian acacia in West Bengal, India has females 0.46–0.65 mm long with coarse body annules, 15–18 m long spear with conus less than half its total length and a short conoid tail (c >1.7–2.8) with 10–15 annules and smooth terminus. T. crassicaudatus leviterminalis n.subsp. differs from T. c. crassicaudatus Williams, 1960 in having a small smooth lip region lacking annules. T. coffeae Siddiqi & Basir, 1959 is fully described from type specimens. ac]19811221     

Sarcocystis dubeyella n. sp. and Sarcocystis phacochoeri n. sp. (Protozoa: Sarcocystidae) from the Warthog (Phacochoerus aethiopicus) in South Africa

ABSTRACT Sarcocystis dubeyella n. sp. and S. phacochoeri n. sp. from muscle fibers of the skeletal musculature of two warthogs in South Africa are described by light and and electron microscopy. Sarcocystis dubeyella sarcocysts are macroscopic (up to 12 mm long and 1 mm wide), with a parasite-induced encapsulation of the host muscle fiber in which the plasma membrane of the latter remained unaltered. The sarcocyst wall is characterized by evenly arranged, irregularly semicircular or rectangular villar protrusions (5.0 T. 2.8-11.0 μm) with indented margins and no specific content. Sarcocystis phacochoeri formed filiform microcysts (up to 4 mm long and 0.13 mm wide). Its cyst wall is provided with tightly packed, molarlike villar protrusions (1.6-3.3 T. 1.7-3.3 μm), with smooth margins, hollow on one side, and with longitudinal condensations of the fine granular matrix at various locations in the interior.     

Observations on the phosphate status and intracellular pH of intact cells, protoplasts and chloroplasts from photosynthetic tissue using phosphorus-31 nuclear magnetic resonance.

Individual pools of intracellular inorganic phosphate (Pi) can be observed in the dark in intact cells, protoplasts and chloroplasts from photosynthetic tissue by using 31P nuclear magnetic resonance (n.m.r.). Estimates for the pH of vacuolar and extravacuolar compartments are reported although it is shown that intracellular pH is determined by the pH of the suspending medium. Mannose treatment of asparagus (Asparagus officinalis) cells and spinach (Spinacia oleracea) protoplasts results in the inhibition of photosynthesis. The mechanism of mannose phosphate sequestration of free Pi is supported by the 31P n.m.r. spectra of mannose-treated tissue. There is a fundamental difference in 31 P n.m.r. spectra of mannose-treated spinach protoplasts and asparagus cells, reflecting a difference in the availability of vacuolar Pi for cellular metabolism in these species. The 31P n.m.r. spectrum of intact spinach chloroplasts is reported.     

Abdominal adipose tissue cytokine gene expression: relationship to obesity and metabolic risk factors

Adipose tissue is a major source of inflammatory and thrombotic cytokines. This study investigated the relationship of abdominal subcutaneous adipose tissue cytokine gene expression to body composition, fat distribution, and metabolic risk during obesity. We determined body composition, abdominal fat distribution, plasma lipids, and abdominal subcutaneous fat gene expression of leptin, TNF-alpha, IL-6, PAI-1, and adiponectin in 20 obese, middle-aged women (BMI, 32.7 +/- 0.8 kg/m2; age, 57 +/- 1 yr). A subset of these women without diabetes (n = 15) also underwent an OGTT. In all women, visceral fat volume was negatively related to leptin (r = -0.46, P < 0.05) and tended to be negatively related to adiponectin (r = -0.38, P = 0.09) gene expression. Among the nondiabetic women, fasting insulin (r = 0.69, P < 0.01), 2-h insulin (r = 0.56, P < 0.05), and HOMA index (r = 0.59, P < 0.05) correlated positively with TNF-alpha gene expression; fasting insulin (r = 0.54, P < 0.05) was positively related to, and 2-h insulin (r = 0.49, P = 0.06) tended to be positively related to, IL-6 gene expression; and glucose area (r = -0.56, P < 0.05) was negatively related to, and insulin area (r = -0.49, P = 0.06) tended to be negatively related to, adiponectin gene expression. Also, adiponectin gene expression was significantly lower in women with vs. without the metabolic syndrome (adiponectin-beta-actin ratio, 2.26 +/- 0.46 vs. 3.31 +/- 0.33, P < 0.05). We conclude that abdominal subcutaneous adipose tissue expression of inflammatory cytokines is a potential mechanism linking obesity with its metabolic comorbidities.     

Observations on thermoregulatory ontogeny of mink (Mustela vison)

(1) We measured cooling rate for neonatal mink during a 10min coldroom (3.9 degrees C) exposure and subsequent warming rate during a 20min incubator (37.2 degrees C) exposure, the behaviour of the kits and the changes in their pelage between 1 and 46d of age, in an attempt to monitor the ontogeny of their thermoregulatory capacity. (2) Body weight of the 1d old kits averaged only 12.8+/-2.3g (n=4), but they gained weight rapidly reaching 226.1+/-28.3g (males, n=4) and 207.6+/-16.1g (females, n=4) at 30-31d of age, and 562.3+/-43.2g (males, n=3) and 435.7+/-35.5g (females, n=4) at 45-46d of age. (3) Body cooling rate (C(rate) ( degrees C/min); n=80) was affected by the age (between 1 and 31d), BW, initial rectal temperature (T(r0)), and sex of the kits, in addition to their body posture (P(cold), 1=extended, 2=curled-up) during coldroom exposure. C(rate) ( degrees C/min)=-0.34-0.02age-0.002BW+0.05T(r0)-0.06sex-0.20P(cold) (R(2)=0.75). (4) Body warming rate (W(rate) ( degrees C/min); n=80) was influenced by the age(2) and rectal temperature of the kit after the coldroom exposure (T(r10)). W(rate)( degrees C/min)=1.24+0.0002age(2)-0.04T(r10) (R(2)=0.76). (5) Kit fur fibre length increased from 5.45+/-0.63mm (males, n=2) and 6.20+/-0.20mm (females, n=3) at 22-23d of age to 9.43+/-1.44mm (males, n=4) and 8.70+/-1.89mm (females, n=4) at 30-31d of age, and to 12.93+/-0.47mm (males, n=3) and 11.38+/-0.41mm (females, n=4) at 45-46d of age, the growth averaging about 0.26mm per day. (6) Under normal circumstances newborn mink kits are hypothermic.Their thermoregulation develops only gradually and is dependent on increase in body mass, insulation and behavioural thermoregulation. Their strategy of survival is based on the ability to withstand hypothermia and on the nutrition and warmth provided by the dam.