Unit Cell Surface Area Research Articles

A triple‐band frequency selective surface for 5G millimeter‐wave communications

AbstractIn this letter, a new triple‐band millimeter‐wave frequency selective surface (FSS) is presented. The proposed FSS structure consists of three slot‐based resonance mechanisms on the single layer of Rogers Diclad880 dielectric. It shows a high compactness with a unit cell surface area of 5.4 × 5.4 mm2. The proposed FSS exhibits a triple‐band bandpass filter characteristics for the allocated 5G millimeter‐wave frequency regions with sufficient bandwidths corresponding to 23.5–24.6, 27–28.5, and 37.5–41 GHz, respectively. Simulation outcomes reveal that the FSS poses polarization insensitive behavior, and maintains high transmission skill for a wide range of incident angles up to 40°. A 40 × 40 FSS panel is fabricated, and the experimental verification is carried out. The outcomes prove that the proposed FSS is suitable for multiband 5G millimeter‐wave filtering applications.

RETRACTED ARTICLE: Synthesis and characterization of magnetite/hydroxyapatite nanoparticles for biomedical applications

During the last few decade, magnetite/hydroxyapatite nanoparticles have attracted much attention for its potential applications in the field of medicine and controlled drug delivery. In the present work, we have intended and synthesized, magnetite/hydroxyapatite nanoparticles by wet-chemical precipitation route. The thermal decomposition of the prepared sample was carried out by Thermogravimetric and Differential Scanning Calorimetry (TG/DSC) analysis upto 1000 °C, it showed that the sample was stable up to 919.2 °C. The phase formation, functional groups, morphology and magnetic property of as-prepared and annealed samples were characterized using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), micro Raman, Field Emission Scanning Electron Microscopy (FE-SEM), Transmission electron microscopy (TEM) and vibrating-sample magnetometer (VSM). By adopting Scherer method detailed structural analysis like the crystallite size, strain, dislocation density, lattice parameter, unit cell volume, surface area and fraction of crystallinity were calculated for as-prepared and annealed HAP samples. The average crystallite size of the as-prepared, annealed at 700 °C, 800 °C and 900 °C are 39, 46, 51 and 65 nm, respectively. The dislocation density, strain and surface area were decreased. FT-IR and Raman spectra showed both as-prepared and annealed samples possessed the characteristic bands of HAP. FE-SEM and TEM images depicted and confirmed the morphological characteristics of HAP. The VSM analysis confirmed that both as-prepared and annealed samples of HAP are in diamagnetic nature. The dielectric constant of as-prepared and annealed samples decreased with increase in annealing temperature whereas the conductivity increases with increase in frequency. The antibacterial property of apatite samples depending on the types of bacterial strains and also activity changed with the crystallite size.

Continuous Variation of Lattice Dimensions and Pore Sizes in Metal-Organic Frameworks.

The continuous variation of the lattice metric in metal-organic frameworks (MOFs) allows precise control over their chemical and physical properties. This has been realized herein by a series of mixed-linker and Zr6-cluster-based MOFs, namely, continuously variable MOFs (CVMOFs). Similar to the substitutional solid solutions, organic linkers with different lengths and various ratios were homogeneously incorporated into a framework rather than being allowed to form separate phases or domains, which was manifested by single-crystal X-ray diffraction, powder X-ray diffraction, fluorescence quenching experiments, and molecular simulations. The unit cell dimension, surface area, and pore size of CVMOFs were precisely controlled by adopting different linker sets and linker ratios. We demonstrate that CVMOFs allow the continuous and fine tailoring of cell-edge lengths from 17.83 to 32.63 Å, Brunauer-Emmett-Teller (BET) surface areas from 585 to 3791 m2g-1, and pore sizes up to 15.9 Å. Furthermore, this synthetic strategy can be applied to other MOF systems with various metal nodes thus allowing for a variety of CVMOFs with unprecedented tunability.

Candida albicans Yeast, Pseudohyphal, and Hyphal Morphogenesis Differentially Affects Immune Recognition.

Candida albicans is a human opportunist pathogen that can grow as yeast, pseudohyphae, or true hyphae in vitro and in vivo, depending on environmental conditions. Reversible cellular morphogenesis is an important virulence factor that facilitates invasion of host tissues, escape from phagocytes, and dissemination in the blood stream. The innate immune system is the first line of defense against C. albicans infections and is influenced by recognition of wall components that vary in composition in different morphological forms. However, the relationship between cellular morphogenesis and immune recognition of this fungus is not fully understood. We therefore studied various vegetative cell types of C. albicans, singly and in combination, to assess the consequences of cellular morphogenesis on selected immune cytokine outputs from human monocytes. Hyphae stimulated proportionally lower levels of certain cytokines from monocytes per unit of cell surface area than yeast cells, but did not suppress cytokine response when copresented with yeast cells. Pseudohyphal cells induced intermediate cytokine responses. Yeast monomorphic mutants had elevated cytokine responses under conditions that otherwise supported filamentous growth and mutants of yeast and hyphal cells that were defective in cell wall mannosylation or lacking certain hypha-specific cell wall proteins could variably unmask or deplete the surface of immunostimulatory ligands. These observations underline the critical importance of C. albicans morphology and morphology-associated changes in the cell wall composition that affect both immune recognition and pathogenesis.

Coordination of Leaf Photosynthesis, Transpiration, and Structural Traits in Rice and Wild Relatives (Genus Oryza)

The genus Oryza, which includes rice (Oryza sativa and Oryza glaberrima) and wild relatives, is a useful genus to study leaf properties in order to identify structural features that control CO(2) access to chloroplasts, photosynthesis, water use efficiency, and drought tolerance. Traits, 26 structural and 17 functional, associated with photosynthesis and transpiration were quantified on 24 accessions (representatives of 17 species and eight genomes). Hypotheses of associations within, and between, structure, photosynthesis, and transpiration were tested. Two main clusters of positively interrelated leaf traits were identified: in the first cluster were structural features, leaf thickness (Thick(leaf)), mesophyll (M) cell surface area exposed to intercellular air space per unit of leaf surface area (S(mes)), and M cell size; a second group included functional traits, net photosynthetic rate, transpiration rate, M conductance to CO(2) diffusion (g(m)), stomatal conductance to gas diffusion (g(s)), and the g(m)/g(s) ratio.While net photosynthetic rate was positively correlated with gm, neither was significantly linked with any individual structural traits. The results suggest that changes in gm depend on covariations of multiple leaf (S(mes)) and M cell (including cell wall thickness) structural traits. There was an inverse relationship between Thick(leaf) and transpiration rate and a significant positive association between Thick(leaf) and leaf transpiration efficiency. Interestingly, high g(m) together with high g(m)/g(s) and a low S(mes)/g(m) ratio (M resistance to CO(2) diffusion per unit of cell surface area exposed to intercellular air space) appear to be ideal for supporting leaf photosynthesis while preserving water; in addition, thick M cell walls may be beneficial for plant drought tolerance.

Size Effects on Adsorption of Hematite Nanoparticles on E. coli cells

Adsorption of engineered nanoparticles (NPs) onto bacterial cells is critical for quantifying nanobio interactions as well as toxicokinetic properties of NPs. The purpose of this work was to study adsorption of hematite (α-Fe(2)O(3)) NPs onto Escherichia coli cells and to determine the particle size effects on the adsorption kinetics. Adsorption of large NPs (76 and 98 nm) on cells reached equilibrium faster (within 30-40 min) than small NPs (approximately 60-90 min). The adsorption rates in mg Fe/(L · s) decreased in the order of 98 nm > 76 nm > 53 nm > 26 nm. However, adsorption rates expressed as the number of adsorbed hematite NPs per unit cell surface area in #/(m2 · s) were faster for small NPs than those for large NPs. To interpret the size effects on adsorption kinetics, the Extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory was combined with interfacial force boundary layer (IFBL) theory. The computed adsorption rates for different sizes had excellent agreement with the experimental data, and they explained that that faster kinetics for smaller NPs could be attributed to faster particle mobility and lower energy barriers in the total interaction energy. This study lays the groundwork for quantifying the kinetic behavior of NPs interacting with microbial cells, and the results provide insight into adsorption processes at the nanoscale.

Universal constant for heat production in protists

Using a high sensitivity differential scanning calorimeter in isothermal mode, we directly measured heat production in eukaryotic protists from 5 phyla spanning over 5 orders of magnitude in carbon biomass and 8 orders of magnitude in cell volume. Our results reveal that metabolic heat production normalized to cell mass is virtually constant in these organisms, with a median of 0.037 pW pg C(-1) (95% confidence interval = 0.022-0.061 pW pg C(-1)) at 5 degrees C. Contrary to allometric models, the relationship between heat production and cell carbon content or surface area is isometric (scaling exponents, 1.056 and 1.057, respectively). That heat production per unit cell surface area is constant suggests that heat flux through the cell surface is effectively instantaneous, and hence that cells are isothermal with their environment. The results further suggest that allometric models of metabolism based on metazoans are not applicable to protists, and that the underlying metabolic processes in the latter polyphyletic group are highly constrained by evolutionary selection. We propose that the evolutionary constraint leading to a universally constant heat production in single-celled eukaryotes is related to cytoplasmic packaging of organelles and surface area to volume relationships controlling diffusion of resources to these organelles.

Coupled changes in the cell morphology and elemental (C, N, and Si) composition of the pennate diatom Pseudo‐nitzschia due to iron deficiency

We investigated the changes in cell morphology and elemental composition with varying iron nutritional status in four oceanic and two coastal isolates of the marine pennate diatom Pseudo‐nitzschia. When iron‐deficient, most isolates exhibited slower specific growth rates (m), reduced maximum photochemical yields (WM), and lower chlorophyll a (Chl a) contents than iron‐replete cultures. Iron‐deficient cells exhibited reduced cell volumes, primarily as the result of decreased valve transapical widths, which increased the valve aspect ratios. The increase in aspect ratios varied among isolates and was not correlated with the degree of growth limitation due to irondeficiency. In all Pseudo‐nitzschia isolates, the mean carbon (Ccell), nitrogen (Ncell), and silicon (Sicell) cell quotas of iron‐deficient cells decreased when compared to iron‐replete cells. Similarly, in five out of the six isolates, the mean C and N quotas normalized per unit cell volume (Cvol and Nvol) of iron‐deficient cells also decreased, but by a lesser extent. In contrast, there were no clear differences in the changes in the mean Si quotas normalized per unit cell surface area (Sisa). The Sicell:Ncell and Sicell : Ccell ratios (quotas normalized per cell) of iron‐deficient cells increased compared to iron‐replete conditions due to greater reductions in C and N cell quotas compared to Si cell quotas. This increase in the Sicell:Ncell ratio was proportional to the changes in the valve aspect ratios. Our results show that iron‐deficient Pseudo‐nitzschia cells acclimate to low iron concentrations by increasing their valve aspect ratios, thus reducing their cell volumes and increasing their surface area‐to‐volume (SA : V) ratios. These changes in cell morphology increase the Si‐containing valve surface area relative to the volume of the internal components, which may then influence the cellular elemental composition, in particular, the Si :N and Si :C ratios.

Photonic bandgap surfaces with interdigitated corrugations

For a given operational frequency, the unit cell surface area of a metallo–dielectric photonic bandgap structure (MBPG) is reduced by increasing the capacitance between adjacent unit cell elements. An MPBG structure possessing interdigitated corrugations is proposed in order to achieve this increase. The structure is incorporated, as the ground plane, in a microstrip transmission line and it is experimentally characterised over the 50 MHz–4 GHz frequency band.

Remodeling of Gap Junctional Channel Function in Epicardial Border Zone of Healing Canine Infarcts

The epicardial border zone (EBZ) of canine infarcts has increased anisotropy because of transverse conduction slowing. It remains unknown whether changes in gap junctional conductance (Gj) accompany the increased anisotropy. Ventricular cell pairs were isolated from EBZ and normal hearts (NZ). Dual patch clamp was used to quantify Gj. At a transjunctional voltage (Vj) of +10 mV, side-to-side Gj of EBZ pairs (9.2+/-3.4 nS, n=16) was reduced compared with NZ side-to-side Gj (109.4+/-23.6 nS, n=14, P<0.001). Gj of end-to-end coupled cells was not reduced in EBZ. Steady-state Gj of both NZ and EBZ showed voltage dependence, described by a two-way Boltzmann function. Half-maximal activation voltage in EBZ was shifted to higher Vj in positive and negative directions. Immunoconfocal planimetry and quantification showed no change in connexin43 per unit cell volume or surface area in EBZ. Decreased side-to-side coupling occurs in EBZ myocytes, independent of reduced connexin43 expression, and is hypothesized to contribute to increased anisotropy and reentrant arrhythmias.

Influence of nutritional weaning on porcine adipocyte beta-adrenergic and adenosine A1 receptors.

Obese and crossbred (X-Bred) pigs were removed from sows at 14 d of age and given ad libitum access to a high-fat, milk-based diet. A subset of pigs fed this diet were killed at 28 and 49 d of age. At 28 d, another subset of pigs was given ad libitum access to a low-fat, grain-based diet and were killed at 31, 35, and 49 d of age (nutritionally weaned for 3, 7, and 21 d, respectively). Dorsal subcutaneous adipose tissue was obtained at death and adipocytes were prepared by incubation with collagenase. A portion of the cells was fixed with osmium to determine size and number; remaining cells were lysed in hypotonic media and centrifuged to yield a crude membrane fraction. The beta-adrenergic receptor (beta-AR) and A1 adenosine receptor (A1R) affinity and number were measured in the membranes by equilibrium saturation ligand binding. Obese pigs had a lower body weight than X-Bred pigs at all ages (P < .05). Obese pigs tended (P for volume > .1 but < .2) to have larger adipocytes than X-Bred pigs. The beta-AR affinity did not differ between obese and X-Bred pigs. There were fewer beta-AR per milligram of membrane protein in obese than in X-Bred pigs at 28 and 49 d of age when fed the high-fat, milk-based diet (P < .01). However, beta-AR number expressed per cell or unit cell surface area did not differ between genetic groups. As pigs of either genetic group continued to be fed the low-fat, grain-based diet, the beta-AR decreased when expressed per milligram of protein or unit cell surface area (P < .05) and tended to decrease when expressed per cell. Obese and X-Bred pigs fed the high-fat, milk-based diet had more beta-AR than respective pigs fed the low-fat, grain-based diet when data were expressed per milligram of protein (P < .01) but not when expressed per cell or unit surface area. The A1R were only detectable in 2 of 16 X-Bred litters but were more developed in adipocytes of obese pigs, being measurable in 8 of 14 litters. The A1R number, expressed per milligram of protein, was lower in obese pigs fed the milk-based diet than in those fed the grain-based diet (P < .05). These findings suggest the decreased beta-AR number after nutritional weaning, or the transition from a high-fat to low-fat diet, may contribute to fat accretion in pigs. Furthermore, the lower number of beta-AR in obese than in X-Bred pigs may contribute to the obesity.

Dehydroxylation of Aluminous Goethite: Unit Cell Dimensions, Crystal Size and Surface Area

AbstractThis work investigates unit cell dimensions, crystal size and specific surface area of aluminous goethite that was progressively dehydroxylated to form hematite. Goethite synthesized from the ferrous system altered to hematite with DTGA maximum increasing from 236° to 273°C for 0 to 30.1 mole % Al-substitution. Unit cell dimensions of goethite and hematite decreased as Al-substitution increased and increased as excess OH increased. The crystallographically equivalent a axis of goethite and c axis of hematite were more sensitive than other axes to the presence of excess structural OH associated with Al-substitution. Specific surface area increased from 147 to 288 m2/g for goethite and from 171 to 230 m2/g for hematite as Al-substitution increased. An increase in specific surface area on heating goethite at temperatures between 200° and 240°C is related to a decrease in the size of coherently diffracting domains of goethite crystals and to the development of pore and structural defects associated with the formation of hematite. The decrease in specific surface area for heating temperatures above 240°C is attributed to the growth of hematite crystals by diffusion.

AC Impedance Measurements on Chava corallina.II. Can the Presence of Plasmalemmasomes be Detected?

Impedance measurements on cells of Chara corallina at frequencies of 10-102 Hz were used to investigate dielectric and geometrical properties of the plasmalemma and tonoplast at different longitudinal positions along the cylindrical surface of the cells. Large (100%) spatial variations occurred in the measured capacitance of some individual cells. Further, for spatially uniform cells, a 100% variation (from cell to cell) in capacitance was observed. Variations in capacitance (at 10-102 Hz) could be partially attributed to variations in: (i) the conductance of the series conductance element, (ii) the dielectric/geometrical properties of the tonoplast and (iii) the conductance of the cell membranes. However, we attribute a substantial part of the variations in capacitance to variations in the area of the plasmalemma per unit area of cell surface arising from extensive folding of the plasmalemma such as that found in plasmalemmasomes (charasomes).

Normal growth and division of Escherichia coli with a reduced amount of murein

The classical model of a murein monolayer for the structure of the murein sacculus of Escherichia coli is at present a controversial matter due to recent advances in the microscopic and biochemical knowledge of this cellular component (B. Glauner, J.-V. Höltje, and U. Schwarz, J. Biol. Chem. 263:10088-10095, 1988; M. Leduc, C. Frehel, E. Siegel, and J. van Heijenoort, manuscript in preparation). We have studied how the limitation in the supply of the murein-specific precursor meso-diaminopimelic acid (DAP) would affect cell growth and morphology as well as murein structure and content per unit of surface area in E. coli strains auxotrophic for DAP. Our observations indicated that the amount of murein per unit of cell surface area could be reduced by about 50% when the external concentration of DAP was equal to or lower than 0.5 microgram/ml. Cells with a reduced amount of murein did not show any detectable alteration in their morphology and characteristics of growth. Furthermore, no major alterations in murein structure were observed by high-pressure liquid chromatography analysis. However, the modification of murein that normally takes place at the initiation of the stationary phase was partially prevented. These results favor the alternative hypothesis of a thin, multilayered structure for the sacculus of E. coli rather than the monolayer model.

Up-regulation of high density lipoprotein receptor activity by gamma-interferon associated with inhibition of cell proliferation.

High density lipoprotein (HDL) binds to cell surface receptors and promotes selective removal of excess cholesterol from intracellular pools. The activity of this receptor is up-regulated when cells become loaded with cholesterol, but the relative degree of up-regulation depends on the growth state of the cells. The current study demonstrates that treatment of proliferating fibroblasts with gamma-interferon (IFN) increases the activity of the HDL receptor in association with a decrease in the rate of cell proliferation. Addition of IFN during the growth phase reduced the number of cells but had little effect on total cell protein, indicating that IFN inhibited cell proliferation but produced larger cells. IFN treatment increased the number of high affinity receptors for HDL on the surface of cholesterol-loaded fibroblasts, whether receptor binding was expressed per cell or per unit of cell surface area, cell protein, or cell cholesterol. IFN treatment also appeared to increase the amount of 110-kDa HDL binding protein in fibroblast membranes that has been postulated to represent the HDL receptor molecule. The IFN-induced increase in HDL receptor activity was associated with an enhanced ability of HDL3 to remove cholesterol from intracellular pools. These results are consistent with the hypothesis that inhibition of cell proliferation increases HDL receptor-mediated transport of excess cholesterol from cells, possibly to rid cells of cholesterol that accumulates in response to a reduced rate of membrane synthesis.

Quantitative immunocytochemical characterization of mononuclear phagocytes: I. Monoblasts, promonocytes, monocytes, and peritoneal and alveolar macrophages

The purpose of the present study was to compare the phenotype of tissue macrophages with that of their precursors in the bone marrow and blood. The phenotype was determined on the basis of the quantitative binding of monoclonal antibodies to cell-surface antigens (antigen F4/80, complement receptor III, Fc receptor II, Ia antigen, common leukocyte antigen, and Mac-2 and Mac-3 antigens) on individual mononuclear phagocytes. Monoclonal antibody binding to cells, detected by the biotin-avidin immunoperoxidase procedure, was quantitated by cytophotometric determination of the amount of enzyme reaction product on cells. The results of this quantitation are expressed as the median of the specific absorbance per unit of cell-surface area (0.25 μm 2) and per cell. Shortly after collection of the mononuclear phagocytes, binding of all monoclonal antibodies except those directed against the common leukocyte and Mac-2 antigens to peritoneal macrophages was enhanced compared with binding to blood monocytes; for alveolar macrophages we found reduced binding of monoclonal antibodies F4/80 and M1/70 (complement receptor III) and enhanced binding of monoclonal antibodies with specificity for the common leukocyte antigen and Mac-2 and Mac-3 antigens. The results obtained with cultured mononuclear phagocytes show that during the development from monoblast to tissue macrophages, monoclonal antibody binding to the various types of mononuclear phagocyte, expressed per unit of cell-surface area, was not significantly altered except that of M3/38 (Mac-2 antigen) to peritoneal macrophages and that of F4/80 and M1/70 (complement receptor III) to alveolar macrophages. Expressed on a per cell basis, the results show an increase in the binding of all monoclonal antibodies except those directed against the Fc receptor II and Mac-3 antigen during the development from promonocytes to peritoneal macrophages; binding of most monoclonal antibodies to alveolar macrophages was considerably lower than that to blood monocytes. It is concluded that the expression of the various cell-surface antigens alters during mononuclear phagocyte differentitaion. The expression changed also during culture, although distinct patterns of alteration could not be distinguished.

Effects of diet restriction on insulin-sensitive phosphodiesterase in rat fat cells

Effects of insulin on insulin-sensitive phosphodiesterase were investigated using fat cells from diet-restricted rats. The enzyme activities in diet-restricted rats were higher in case of 0 to 30 nmol/L insulin concentrations than in ad lib fed rats. In fat cells from the diet-restricted rats, the curves shifted to the left and half-maximum stimulation was obtained at 0.04 nmol/L, compared to that of 0.18 nmol/L in ad lib fed rats. Specific binding of insulin for fat cells from diet restricted and ad lib fed rats was 6.0% and 5.4% 2 × 10 5 cells , respectively. However when insulin binding was expressed per unit cell surface area, it was significantly increased in fat cells from diet-restricted rats compared with that from control rats. These results suggest that the insulin effector system related to the phosphodiesterase activation is improved in fat cells from diet-restricted rats, in particular, sensitivity to insulin. These increases in sensitivity to the phosphodiesterase are possibly due to improvements of insulin receptor binding.

Modulation of interferon-alpha and interferon-gamma receptor expression during T-lymphocyte activation and proliferation.

Freshly isolated normal human T lymphocytes constitutively expressed receptors for interferon-alpha (IFN-alpha) and IFN-gamma. Upon activation, the number of IFN-alpha receptors increased, paralleling the increases in cell size to give a nearly constant density of IFN-alpha receptors. In contrast, activation of T lymphocytes with phytohemagglutinin (PHA), concanavalin A (ConA), or phorbol myristate acetate (PMA) for 18 h decreased the specific binding of radiolabeled [Cys-Tyr-Cys] rIFN-gamma to acid-washed cells. Scatchard analysis demonstrated that the decreased binding was due to a reduction in the number of high affinity IFN-gamma receptors. Moreover, resting T lymphocytes had a single class of high-affinity IFN-gamma receptors, whereas the activated cells appeared to have both high- and lower-affinity IFN-gamma binding sites. When normalized for differences in cell size, the number of high-affinity IFN-gamma receptors per unit cell surface area was approximately twofold lower on activated than on resting T lymphocytes. At least part of the decrease was due to receptor downregulation by endogenously produced IFN-gamma, since monoclonal antibodies to IFN-gamma prevented a large portion of the PHA-induced decrease in IFN-gamma receptors.

Effect of insulin on lipolysis in adipose tissue of rats of different ages.

Several authors have not been able to find any antilipolytic effect of insulin in adipose tissue "in vitro". We investigated the possible role of cell size and/or age of donors on this phenomenon. The lipolytic rates (glycerol release per cell) were lower in the small cells of the 4-6 weeks old rats than in the larger cells of the 25-30 weeks old animals; however, the difference disappeared when the data were expressed per unit of cell surface area. Insulin (0.5-50 ng/ml) failed to inhibit both maximally and submaximally noradrenaline stimulated lipolysis in the adipocytes of the young rats, but its antilipolytic action was fully restored by using glucose-free medium. Therefore, at our experimental conditions, a glucose dependent factor, possibly involving the preferential hydrolysis of newly synthetized triglycerides, seems to blunt or to mask the insulin induced inhibition of glycerol release. Relatively higher rates of glucose metabolism and a lower lipolysis in small fat cells might explain the difference in the action of insulin on glycerol release in the adipose tissue of young rats as compared to the older ones.

Evolution de la capacité d'estérification des acides gras dans les adipocytes de rat avant le sevrage : effet de la suralimentation lactée

During the suckling period, lipid storage in rat adipose tissue arises from exogenous triglycerides, as milk contains a large amount of lipid. In the present work, we studied the effect of overfeeding during the suckling period on the developmental pattern of the fatty acid esterification pathway in fat cells. Early overfeeding was induced by restricting litter size; at 2 days of age, the pups were randomly distributed to form litters of 4 (overfed group) or 8 (controls). During the suckling period the activity of lipoprotein lipase (LPL), glycerophosphate dehydrogenase (G3PDH), glycerophosphate acyl transferase (GPAT) and acyl CoA ligase were measured in isolated fat cells from the inguinal adipose tissue. As early as 10 days of age, plasma triglyceride levels were increased in overfed pups as compared to the controls and, in these animals, the adipose tissue was overdeveloped, mainly due to fat cell hypertrophy. At that age, overfeeding induced a significant increase in LPL and GPAT activities, but acyl CoA ligase and GPDH were not modified in overfed pups. Fat cell hypertrophy appeared to be responsible for the increased GPAT activity in the overfed pups. On the contrary, the effect of overfeeding on LPL activity was not only related to fat cell enlargement, as the enzyme activity continued to increase in the overfed rats when expressed per unit of cell surface area. These results show that overfeeding during the suckling period rapidly induced an increase in the fat storage capacity of the adipose tissue. This suggests that circulating triglyceride levels could regulate directly or through hormonal control the activity of the fatty acid esterification pathway in fat cells.