Basal maintenance

Intestinal cytochrome P-450, in common with its hepatic isozymes, is induced by a wide variety of xenobiotics. Not only intraluminal iron but also selenium is critically required for basal maintenance of intestinal cytochrome P-450 content and its dependent mixed-function oxidase. Accordingly, acute deprivation of either element for as short a period as a single day reduced basal intestinal cytochrome P-450 content by limiting the formation and/or availability of its prosthetic heme (Pascoe et al. 1983). Whereas both intraluminal iron and selenium were required for maintenance of the prosthetic apocytochrome moiety of the constitutive intestinal isozyme, only intraluminal selenium was required for the viability of apocytochrome of the P-naphthoflavone-inducible P-448 (Pascoe and Correia 1985). 

Animal nutritionists have developed formulas to guide them in recommending the amount of food to feed animals in captive situations such as in zoos. First, the number of calorics needed to maintain the animal while at rest is determined—this is called the basal metabolic rate (BMR). In general, a reptile s BMR is only 15 percent that of a placental mammal, while a bird s is quite a bit higher than both a reptile s and a mammal s. For all animals, the number of calories they should receive on a maintenance diet is twice that used at the basal metabolic rate. A growing animal should receive three times the number of calories at the BMR, while an animal in the reproductive phase should receive four to six times the BMR. 

The cytoskeleton is involved in the maintenance of cell shape and cytoplasmic processes (e.g., microvilli). In polarized epithelial cells, distinct cyto-cortical cytoskeletal complexes are associated with the apical and basal-lateral domains of the plasma membrane (Rodriguez-Boulan and Nelson, 1989 Mays et al., 1994). 

Once TBW has been restored, the volume of maintenance fluid equals the basal fluid requirement plus ongoing exceptional losses. If the pathophysiologic process leading to TBW depletion has not been identified and corrected (or accounted for in the calculation of maintenance fluid requirements), TBW depletion will quickly recur. To review the concepts involved in the calculation of replacement fluids for a representative patient (see Patient Encounter 2). 

FIG. 2. The formation of the apical protein complex involves two distinct steps. Bazooka is localized apically in the epithelium from which neuroblasts are derived. In the interphase (G2), delaminating neuroblast formation of the apical complex is initiated. It is thought that Baz acts to allow neuroblasts to retain the apical/basal polarity inherent in the epithelium. Baz recruits Insc to the neuroblast apical stalk during delamination before Pins becomes part of the complex. During this initiation step Baz, Insc and Pins are part of a linear hierarchy. However following delamination and during mitosis, the maintenance of the apical localization of each of these proteins requires all three proteins. 

In Pins - embryos the initiation steps of apical complex formation occur normally. However, this complex cannot be maintained in mitotic neuroblasts. Hence, the importance of the maintenance of this complex for asymmetric cell division can be ascertained by assessing how Pins- neural progenitors divide. Pins- embryos exhibit all of the defects seen in insc mutants. Mitotic spindle orientation is defective. In the cells of mitotic domain 9 the 90° reorientation, which normally occurs in wild-type resulting in the orientation of the spindle along the apical—basal axis (Fig. 3A), fails to occur in the mutant (Fig. 3B). Mitotic spindle orientation of neuroblasts in the segmented CNS, deduced from DNA staining, also often fails to... 

The postsynaptic membrane opposite release sites is also highly specialized, consisting of folds of plasma membrane containing a high density of nicotinic ACh receptors (nAChRs). Basal lamina matrix proteins are important for the formation and maintenance of the NMJ and are concentrated in the cleft. Acetylcholinesterase (AChE), an enzyme that hydrolyzes ACh to acetate and choline to inactivate the neurotransmitter, is associated with the basal lamina (see Ch. 11). 

The assay for pantothenic acid in whole blood, serum, urine, and cerebrospinal fluid is described here. Lactobacillus plantarum ATCC No. 8014 (formerly L. arabinosus) is used for the assay. The basal medium for assay (Table 2) is made up in double strength 2.5-ml portions of the medium are distributed into 10-ml borosilicate micro-Fembach flasks provided with aluminum caps (H18). Solutions to be assayed are added and distilled water used to bring the volume to 5 ml. The techniques for maintenance and assay are the same as those for L. casei (B12). Full growth at 37° takes 3 days. 

The organism is L. casei ATCC No. 7469. The basal medium (J6) has been modified it contains twice the concentration listed in Table 10a, and is stable when stored in an amber bottle in the cold. It is kept free from contamination with a volatile preservative. L. casei was maintained in medium given in Table 10b 10 ml of this medium is dispensed into screw-capped tubes and autoclaved for 30 minutes at 118°, 16 psi. It should be transferred every 2 weeks one drop of an 18-hour culture into 10 ml of maintenance medium suffices with subsequent 18-hour incubation at 37°. Cultures should be stored at 4°. 

Blood of normal subjects was obtained from an antecubital vein, diluted 1 5 with pH 4.5 buffer,2 and autoclaved 30 minutes to convert bound cobalamin into its microbiologically active form serum was treated like blood. This procedure allowed estimation of total vitamin Bi2. For the subsequent inoculation of specimens (a) E. coli as a loopful from nutrient agar suspended in 25 ml of medium, (b) L. leichmannii, an 18-hour culture diluted 1 10 in basal medium, (c) E. gracilis, strain Z, and (d) O. malhamensis are inoculated directly from a 5-day culture grown in liquid maintenance medium. One drop into a culture flask served as inoculum. The bacteria required 18-hours for full growth protozoa, 4-5 days. 

The basal diet was a measured, laboratory controlled diet based on ordinary foods fed in sufficient quantities to meet caloric requirements of the 127 subjects for weight maintenance and meeting or exceeding the National Research Council Daily Recommended Nutrient Intakes. 

A number of ocular surface disorders collectively termed as Dry Eye Syndromes have also been associated with the conjunctiva. For example, a deficiency and/or imbalance in compositions of the tear film is often found on the ocular surface during keratoconjunctivitis sicca. Since the conjunctiva plays a direct role in the maintenance of the tear fluid stability via secretion of mucin [1] by its resident goblet cells [4] and basal fluid secretion driven by electro-osmotic gradients across the tissue [3], the conjunctiva is a well deserved, but not intensively studied, target of interest in research efforts aimed against combating Dry Eye Syndromes. 

Energy expenditure comes in the form of basal metabolism, maintenance of body temperature, and physical exercise. 

In one case report a 37-year-old male maintenance fitter was accidentally exposed to a large cloud of hot acetic acid while disconnecting a pressurized pump. The patient suffered first-degree burns on the hands and face and developed progressive dyspnea. At 3 months there were persistent extensive crackles in the basal area of the lungs, widespread bronchial inflammatory changes, and diffuse moderate interstitial pneumonitis that promptly improved after treatment with corticosteroids and bronchodilators. 

Catabolism and anabolism are often inversely regulated to provide balance for maintenance of the body s basal metabolic rate and to enable specific physiologic functions of organs. 

Upon s.c. injection, the insulin experiences an increase in pH towards more neutral values and, consequently, appears to precipitate in the subcutaneous tissue. It resolubilizes very slowly and hence a greatly prolonged duration of release into the bloodstream is noted. Consequently, a single daily injection supports the maintenance of acceptable basal blood insulin levels, and insulin molecules are still detected at the site of injection more than 24 h after administration. 

There are two main hypotheses about the involvement of endogenous opioid systems in the maintenance of self-injurious behaviors (Sandman, 1988 Buitelaar, 1993). The pain hypothesis suggests that in some subjects self-injury does not induce pain because excessive basal activity of opioid systems in the CNS has led to an opioid analgesic state. The addiction hypothesis posits that particularly repetitive and stereotyped forms of self-injury stimulate the production and release of en-dogeneous opioids. Therefore, chronic maintenance of self-injury may be due to addiction to endogenous opioids or to positive reinforcement by a central release of opioids triggered by the self-injurious behavior. Irrespective of which hypothesis one favors, treatment with opiate antagonists seems to be a rational approach. 

---