Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory.

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1×10^{14} and 7.7×10^{14}  electrons/cm^{3}. We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (<15  MV/m) and reach over 300  MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels.

Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host

The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.

Catatonia and its clinical course: Descriptive analysis of 12 consecutive cases in a general hospital psychiatric inpatient unit

Introduction

Scientific research regarding Catatonia is limited to individual clinical cases. Few well-design studies investigating its clinical course or therapeutic options have been carried out. We aimed to describe a sample of consecutive Catatonic patients admitted to the Basurto's Hospital Adult Psychiatric Inpatient Unit to obtain more data about its clinical presentation.

Material and methods

Subjects diagnosed of Catatonia anytime during admission were included (n = 12). Subject's admission dates ranged between December 2008 to September 2010. Catatonia was diagnosed following DSM-IV-TR criteria. Data was retrospectively obtained reviewing subject's clinical notes.

Results

The sample was predominantly composed of women (66.7%). Media of age was 55.3 years. All subjects reported previous mental illness. More prevalent diagnosis were Schizophrenia (33.2%), Bipolar Disorder (33.2%), Non Specified Psychotic Disorder (16.6%), Schizoaffective Disorder (8.3%) and Recurrent Depressive Disorder (8.3%). Nine subjects (75%) reported previous admission to a psychiatric unit. No subjects had previously suffered from Catatonia and only 2 had previously received electroconvulsive therapy (ECT). More frequent catatonia subtype was retarded (66.7%) with no subjects presenting with malignant catatonia. CGI at admission showed a media of 6.64.

Regarding treatment, 83.3% did not recover with benzodiazepines and needed ECT anytime during admission. Media admission length was 36.17 days.

Conclusions

Catatonia was more frequently observed in female, middle-aged women with no previous history of catatonia or ECT treatment but a history of previous psychotic or affective illness and hospital admissions. Symptom severity was very high and thus required aggressive treatment and longer hospital stays in order to achieve recovery.

Role of neuronal voltage-gated K(+) channels in the modulation of the nitrergic neurotransmission of the pig urinary bladder neck

BACKGROUND AND PURPOSE

As nitric oxide (NO) plays an essential role in the inhibitory neurotransmission of the bladder neck of several species, the current study investigates the mechanisms underlying the NO-induced relaxations in the pig urinary bladder neck.

EXPERIMENTAL APPROACH

Urothelium-denuded bladder neck strips were dissected and mounted in isolated organ baths containing a physiological saline solution at 37 degrees C and continuously gassed with 5% CO(2) and 95% O(2), for isometric force recording. The relaxations to transmural nerve stimulation (EFS), or to exogenously applied acidified NaNO(2) solution were carried out on strips pre-contracted with phenylephrine, and treated with guanethidine and atropine, to block noradrenergic neurotransmission and muscarinic receptors, respectively.

KEY RESULTS

EFS (0.2-1 Hz) and addition of acidified NaNO(2) solution (1 microM-1 mM) evoked frequency- and concentration-dependent relaxations, respectively. These responses were potently reduced by the blockade of guanylate cyclase and were not modified by the K(+) channel blockers iberiotoxin, charybdotoxin, apamin or glibenclamide. The voltage-gated K(+) (Kv) channels inhibitor 4-aminopyridine, greatly enhanced the nitrergic relaxations evoked by EFS, but did not affect the NaNO(2) solution-induced relaxations.

CONCLUSIONS AND IMPLICATIONS

NO, whose release is modulated by pre-junctional Kv channels, relaxes the pig urinary bladder neck through a mechanism dependent on the activation of guanylate cyclase, in which post-junctional K(+) channels do not seem to be involved. Modulation of Kv channels could be useful in the therapy of the urinary incontinence produced by intrinsic sphincteric deficiency.

Swelling of the leg, deep venous thrombosis and the piriformis syndrome

BACKGROUND

The piriformis syndrome, which was first described 60 years ago, is a well recognized cause of sciatica, leg pain and low back pain, due to the entrapment of the sciatic nerve in the piriformis and other rotator muscles. Very few complications relating to this syndrome have been described.

AIMS

To discuss how the piriformis syndrome may cause venous engorgement in the lower limb, and how the piriformis syndrome should be included as a possible cause of acute deep venous thrombosis in a not initially swollen leg. Both complications can occur independently.

METHODS

Two cases of swelling of the leg and acute deep venous thrombosis independently associated with the piriformis syndrome are presented.

CONCLUSIONS

Swelling of the leg and deep venous thrombosis are possible complications of the piriformis syndrome that occur due to entrapment of nerves and vessels within the leg, secondary to a severe spasm and hypertrophy of the piriformis and other rotator muscles.

NK2 tachykinin receptors mediate contraction of the pig intravesical ureter: tachykinin-induced enhancement of non-adrenergic non-cholinergic excitatory neurotransmission

The current study was designed to characterize the functionally active tachykinin receptors involved in tachykinin-elicited contractions in the pig intravesical ureter, and to investigate the possible modulation exerted by the natural tachykinins substance P (SP) and neurokinin A (NKA) on the non-adrenergic non-cholinergic (NANC) excitatory ureteral neurotransmission. In pig intravesical ureteral strips pretreated with phosphoramidon (10(-5) mol/L) to block the endopeptidase activities, isometric force recordings showed that SP, NKA, and the NK2 receptor selective agonist [beta-Ala(8)]-NKA (4-10), all three induced contractions, with the following potency order: NKA > [beta-Ala(8) ]-NKA (4-10) > SP. [Sar(9), Met(O(2))(11)]-SP and senktide, selective agonists of the NK1 and NK3 receptors, respectively, failed to modify the ureteral tone. Urothelium removal and incubation with tetrodotoxin (10(-6) mol/L), phentolamine (10(-7) mol/L), propranolol (3 x 10(-6) mol/L), atropine (10(-7) mol/L) and indomethacin (3 x 10(-6) mol/L), did not alter the contraction induced by a submaximal (10(-7) mol/L) dose of [beta-Ala(8)]-NKA (4-10). MEN 10,376 (10(-8)-10(-7) mol/L), a NK2 receptor antagonist, reduced the contraction to 3 x 10(-8) mol/L NKA. GR 82334 (10(-6) -10(-5) mol/L) and SR 142801 (10(-8)-10(-7) mol/L), selective antagonists of the NK1 and NK3 receptors, respectively, did not modify that contraction. In pig intravesical ureteral strips in NANC conditions, SP and NKA induced a potentiation of the contractions to electrical field stimulation (EFS) and to exogenous ATP. The results suggest that the tachykinins evoke a direct contraction of pig intravesical ureteral strips through NK2 receptors located in the smooth muscle. SP and NKA exert an enhancement of the NANC excitatory neurotransmission of the pig intravesical ureter.

[Imported myiasis: 7 cases of cutaneous parasitism caused by Dermatobia hominis flie larvas]

Myiasis is the parasitism of organs and tissues of warm-blooded vertebrates by flies larvae. D hominis is a flie geographically restricted to tropical America from Mexico to northern Argentina. The adult flie, which is not hematophagous, needs to put its eggs on the abdominal surface of hematophagous arthropods which serve as carriers of future larvae which are deposited on the skin of the hosts (mammals, birds and accidentally men) when biting. Seven patients (two females) aged 7 to 35 years old, of different nationalities, recalled receiving mosquito bites, after staying in tropical American areas in the previous forty days. They presented furuncle-like lesions in exposed surfaces of the body. These lesions, 2-3 cm long, pruritic and mildly tender, broke and released a serous or serohematic fluid. Through the resulting opening, it was possible to partially observe the larva. Larvae were extracted by manual pressure (4) or surgical incision (3) and identified as D hominis larvae. Diagnosis of dermatobiasis, an imported myiasis, must be based on the characteristics of lesions and the previous residence in endemic areas of America.

Tachykininergic excitatory neurotransmission in the pig intravesical ureter

PURPOSE

The present investigation was designed to study the role played by neurokinin A (NKA) in the non adrenergic non cholinergic (NANC) neurotransmission of the pig intravesical ureter.

MATERIALS AND METHODS

We used immunohistochemical techniques to evidence the distribution of NKA-immunoreactive (NKA-IR) fibers in the pig intravesical ureter. We have also performed isolated organ bath experiments to release endogenous tachykinins from ureteral nerves and to characterize the functionally active receptor through which endogenous ligands evoke contraction, and to show the effect of exogenous tachykinins on intravesical ureteral smooth muscle.

RESULTS

NKA-IR fibers were found penetrating through ureteral adventitia and distributed in the subepithelial and muscular layers. NKA-IR fibers were not found around small arteries supplying the ureter or in the associated intramural ganglia. Electrical field stimulation (EFS, 1 ms duration, 2 to 16 Hz, 20 s trains) performed in NANC conditions evoked frequency-dependent contractions which were reduced by capsaicin (10-5 M) and GR 94800 (3 x 10-8 M), sensory neurotoxin and NK2 receptor antagonist, respectively. Contractions to EFS were abolished by tetrodotoxin (10-6 M). Exogenous NKA and substance P (SP) induced dose-dependent contractions, characterized by an increase of the ureteral basal tone, NKA being more potent than SP.

CONCLUSIONS

These results suggest that tachykinins, especially NKA, released from capsaicin-sensitive primary afferents, are involved in the NANC excitatory neurotransmission, contracting the smooth muscle via NK2 receptors activation, in the pig intravesical ureter. NKA at this level does not seem to participate in the regulation of local blood flow, plasmatic extravasation or ganglionar transmission.

A2B adenosine receptors mediate relaxation of the pig intravesical ureter: adenosine modulation of non adrenergic non cholinergic excitatory neurotransmission

1. The present study was designed to characterize the adenosine receptors involved in the relaxation of the pig intravesical ureter, and to investigate the action of adenosine on the non adrenergic non cholinergic (NANC) excitatory ureteral neurotransmission. 2. In U46619 (10(-7) M)-contracted strips treated with the adenosine uptake inhibitor, nitrobenzylthioinosine (NBTI, 10(-6) M), adenosine and related analogues induced relaxations with the following potency order: 5'-N-ethylcarboxamidoadenosine (NECA) = 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA) = 2-chloroadenosine (2-CA) > adenosine > cyclopentyladenosine (CPA) = N6-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide (IB-MECA) = 2-[p-(carboxyethyl)-phenylethylamino]-5'-N-ethylcarboxamidoaden os ine (CGS21680). 3. Epithelium removal or incubation with indomethacin (3 x 10(-6) M) and L-N(G)-nitroarginine (L-NOARG, 3 x 10(-5) M), inhibitors of prostanoids and nitric oxide (NO) synthase, respectively, failed to modify the relaxations to adenosine. 4. 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 10(-8) M) and 4-(2-[7-amino-2-(2-furyl) [1,2,4]-triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385, 3 x 10(-8) M and 10(-7) M), A1 and A2A receptor selective antagonists, respectively, did not modify the relaxations to adenosine or NECA. 8-phenyltheophylline (8-PT, 10(-5) M) and DPCPX (10(-6) M), which block A1/A2-receptors, reduced such relaxations. 5. In strips treated with guanethidine (10(-5) M), atropine (10(-7) M), L-NOARG (3 x 10(-5) M) and indomethacin (3 x 10(-6) M), both electrical field stimulation (EFS, 5 Hz) and exogenous ATP (10(-4) M) induced contractions of preparations. 8-PT (10(-5) M) increased both contractions. DPCPX (10(-8) M), NECA (10(-4) M), CPCA, (10(-4) M) and 2-CA (10(-4) M) did not alter the contractions to EFS. 6. The present results suggest that adenosine relaxes the pig intravesical ureter, independently of prostanoids or NO, through activation of A2B-receptors located in the smooth muscle. This relaxation may modulate the ureteral NANC excitatory neurotransmission through a postsynaptic mechanism.

Vasorelaxant effect of the analgesic clonixin on rat aorta

1. A novel vasorelaxant effect of clonixinate of L-lysine (Clx), analgesic and anti-inflammatory, was studied in rat aortic rings. 2. Clx completely relaxed aortic rings contracted by KCl 70 mM and together with its analog flunixin exhibited lesser potency but equal efficacy than verapamil. In comparison, indomethacin, which is a more potent cyclo-oxygenase inhibitor relaxed only about 40% of the maximal contraction of aortic rings. 3. Furthermore, Clx antagonized Ca2+ dependent aortic contraction and BAY K-8644 induced aortic contraction suggesting its calcium antagonist character. 4. From these results it can be concluded that the hypotensive effect seen in rats in vivo after Clx i.v. injection arises because of vasodilatory effect of Clx and gives further support to the proposal that the pharmacological mechanism of action of Clx should be calcium antagonism.

[Depression in the early course of schizophrenia]

Depressive syndromes in schizophrenia are reported in the prodromal stage of the early course, during the first or later psychotic episodes, but also after the fading out of an acute episode and as a precursor of relapse. According to these multiple conditions several explanations also exist as to how to understand depression in schizophrenia. Some authors interpret it as an elementary part of the schizophrenic symptomatology, which is only masked by positive symptoms (revealed depression). However, it can also be understood as a reactive depression or as caused by neuroleptic treatment, as part of the negative syndrome or as co-morbidity. In the ABC-Schizophrenia-Study, depression in the early course was analysed for patients in their first psychotic episode at index admission and an ICD-9 diagnosis of schizophrenia (ICD 295). In 81% of this sample depression was observed, beginning on average 4.3 years prior to index admission. In 42% of the patients depression began in the prepsychotic phase. In 18% the positive and the depressive syndrome developed within one month, and in 21% depression started after the first positive symptom occurred. We could only observe a clear sequence of depressive, negative and positive symptoms in the subgroup characterised by prepsychotic depression. A clear order of negative and positive symptoms was not observed in the other groups. Patients without depression in the early course have lower symptom levels at index admission. They present less positive symptoms (CATEGO-subscore DAH), fewer behavioural disturbances (subscore BSO) and also lower scores of non-specific symptoms (subscores SNR and NSN). More than 80% of the patients with depression in the early course also had a simple depression (as defined by the CATEGO-syndrome SD). Contrary to this, only 20% of the patient group without depression in the early course have positive SD values. Comparable percentages of males and females have depression in the early course, but in females depression begins more frequently in the prepsychotic phase, whereas in the male subgroup it more often starts postpsychotically, i.e. after the onset of the first psychotic symptom.

Population study of horizontal cells in live carp retinas using microinjections of horseradish peroxidase

In order to randomly sample horizontal cells (HCs) of carp retina, horseradish peroxidase (HRP) was delivered into axon terminals by means of vitreally inserted micropipettes in live fish. Survival time was extended to several hours to permit label diffusion into HC somata. A function measuring the relative complexity of cell contours was defined in order to help classify HCs according to their morphological types. The histogram of measurement from 313 HCs showed three modes fitting normal distributions. The numbers of cells in each group were 267, 36 and 10, respectively, representing a relative population of 85.3% H1s, 11.5% H2s and 3.2% H3s. It is suggested that cone HC somata are extended in a monolayer constituted by predominant type-H1 with interspersed groups of both type-H2 and type-H3 cells.

[Clinical and urodynamic study of enuresis in a juvenile male population]

We carried out a clinical and urodynamic assay of 100 cases of enuresis of a male population of ages ranging from 17 to 25. 64% displayed urodynamic alterations and these were significantly greater (p less than 0.005) amongst those suffering from nocturnal enuresis with diurnal symptoms (90%) than amongst those suffering from nocturnal enuresis only (59%). 36% of the patients did not display any urodynamic alteration. The urodynamic dysfunction most commonly displayed was vesical instability (46%). The other urodynamic dysfunctions found were 18% of the total, and detrusor contraction alteration constituted 10% of these (2 of the cases corresponded to vesical-urethral neurogenic dysfunction). The presence of minimum latent rachichisis was accompanied by urodynamic alterations in a significantly larger proportion (p less than 0.005) than in individuals not displaying this. The three case of wide-scale rachischisis were accompanied by urodynamic alterations corresponding to vesico-urethral neurogenic dysfunction. The case of secondary enuresis displayed neither urodynamic nor radiological alterations. Juvenile age enuresis displayed similar characteristics to infantile enuresis, although the percentage of vesical instability was lower. However, detrusor contraction alterations increased and the presence of previously non diagnosed vesico-urethral neurogenic dysfunctions was displayed.

Fast activity and oscillatory potential of carp retina in the frequency domain

There are two kinds of fast activity in the ERG: fast retinal potentials (FRP), an irregular series of spiky wavelets and oscillatory potentials (OP), a rhythmic sequence of events. Corneal ERG from nine intact young carps, evoked by extended pulses of diffuse white light under mesopic adaptation, displayed two different groups of wavelets related to ON and OFF, respectively. Stimulation and recording conditions were established to permit separate Fourier analysis of both groups of wavelets. Power distributions of normalized ON spectra showed both a wide dispersion and a high inter-subject variability. All normalized OFF spectra showed, instead, components within a narrow band from 52 to 56 Hz, most of them maximum relative power peaks. It is concluded that FRP originating in highly labile sources dominate ON fast activity, while the predominant OFF fast activity are OP originating in a stable discrete source.

Chronic effects of an alpha-glucosidase inhibitor (Bay o 1248) on intestinal disaccharidase activity in normal and diabetic mice

Bay o 1248 is a potent alpha-glycosidase inhibitor that reduces postprandial hyperglycemia when administered p.o. with sucrose or maltose. The compound binds to and competitively inhibits the alpha-disaccharidases and is also readily absorbed across the intestinal mucosa. To evaluate its effect on the activity of disaccharidases and on metabolic control, groups of obese diabetic mice (C57BLKsJ db/db) were given the drug for periods of 3, 7 and 84 days as a drug food mixture (5 or 10 mg/100 g of food). Nondiabetic mice of the same strain were dosed for 3 and 7 days. The drug did not influence body growth, food intake or fasting blood glucose. However, urine glucose excretion was significantly decreased at the higher dose in the diabetic mice. The drug had no effect on the protein content of jejunum (proximal and middle thirds) or ileum (distal third) of the small intestine. The activity of sucrase and maltase was significantly decreased in practically all segments of the small intestine in both diabetic and nondiabetic mice. These changes were evident after 3 days of drug administration. Lactase was not affected by the drug. The mechanism underlying these changes, although unclear, is of significant interest and deserves further investigation.

Response of activity of jejunal disaccharidases and pancreatic amylase in young and middle-aged rats to a high carbohydrate diet

Sprague-Dawley rats fed a nonpurified diet from weaning to 3 mo (young) or 12 mo (middle aged) of age were fed a low (5 cal%) starch (LST) purified diet for 2 wk. They were then fed a high (70 cal%) starch (HST) purified diet for up to 4 wk. Body weights of both age groups were greater in rats fed the LST than in those fed nonpurified diet throughout. The young, but not the middle-aged, group continued this gain while consuming HST. The levels of activity of intestinal disaccharidases of upper (proximal one-third) and lower (middle one-third) jejunum, and pancreatic alpha-amylase were lower in rats fed LST diet in both age groups than in rats fed HST. Similar increases of specific (per protein or DNA) activity were observed in both age groups throughout the first three (disaccharidase) to four (pancreatic alpha-amylase) days of feeding HST. Values of specific activity of the middle-aged group returned to initial levels with continued feeding of HST. In contrast, values in the young group tended to plateau (disaccharidases) or continued to increase (alpha-amylase). Differences in adaptability over 1 mo were most dramatic for alpha-amylase and sucrase, but negligible for lactase.

Effect of a high-dextrose diet on sucrase and lactase activity in jejunum of obese mice (C57BL/6J obob)

The activities of intestinal disaccharidases are known to be responsive to changes in the dietary intake of carbohydrates in the adult rat. Little is known, however, regarding the activities of these enzymes in obese subjects and how they are affected by differing carbohydrate intakes. To evaluate the effect of carbohydrate intake on the activity of intestinal disaccharidases in obesity, we used the genetically obese mouse C57BL/6J obob as an experimental model. Representing an example of early-onset obesity and mature-onset diabetes, this animal is characteristically hyperinsulinemic and hyperglycemic. Groups of obese mice and lean littermates were fed for 7 weeks equal amounts of either high-dextrose or low-dextrose isoenergetic diets. Sucrase, maltase, and lactase activities were measured on intestinal homogenates from the proximal and middle portions of the jejunoileum (upper and lower jejunum). Results were expressed as activity per tissue protein as well as total activity. Obese mice were found to have consistently greater total activity of both sucrase and maltase than their lean littermates, mostly as a result of increased intestinal size. Total lactase activity, however, was similar in the upper jejunum in both obese and lean mice, largely related to a decreased specific activity in obese mice. All mice fed the high-dextrose diet had significantly increased total activity of all disaccharidases studied when compared to the low-dextrose-fed animals, except for the lactase activity in the lower jejunum, where no differences were found in either group. Increases in activity related to high carbohydrate intake were a result of increases in specific activity.

Dietary regulation of intestinal lactase and sucrase in adult rats: quantitative comparison of effect of lactose and sucrose

To characterize the mechanisms leading to dietary evoked increases of lactase and sucrase activities by carbohydrates, we performed a quantitative comparison of the effects of lactose and sucrose on the corresponding disaccharidases in the jejunum of 2-month-old rats. For 7-10 days the rats were fed a low-starch (5 cal%), high-fat (73 cal%) diet, and for various periods of time (3-72 h) were given an isocaloric sucrose or lactose (20, 40, or 70 cal%) diet. Lactase and sucrase activities in jejunal homogenates were significantly increased within 3 h after the initial feeding of the sucrose (40 cal%) diet. After 3 h of feeding the sucrose diet, sucrase activity gradually increased and reached its maximum at 24 h, whereas lactase activity did not exhibit further change. Increased intake of sucrose led to an increase of lactase and sucrase activity. Within a range of doses of digestible amounts of lactose, the effect of diet containing lactose on these disaccharidase activities was similar to the effect of the diet containing sucrose. This similarity suggests the important role of the common constituent sugar, i.e., glucose. Further, analyses of response to these disaccharides along the villus-crypt axis revealed that the increase of lactase activity occurs at a more apical and broader locus of cohort of epithelial cells along the height of the villus than that of sucrase, suggesting that different mechanisms are involved in dietary regulation of lactase and sucrase.

Precocious increase of sucrase activity by carbohydrates in the small intestine of suckling rats. II. Role of digestibility of sugars, osmolality, and stomach evacuation in producing diarrhea

The mechanisms of carbohydrate-induced diarrhea in suckling rats were investigated with respect to osmolality and type of sugar in the milk. Groups of 12-day-old rats were gavage fed either a basic low carbohydrate milk formula [10.8% fat; 8% protein; 1.4% carbohydrate (weight/volume)] or basic formula with added sucrose, fructose, lactose, or glucose polymers, all as 13% (weight/ volume). All formulas were isocaloric. Their corresponding osmolalities were 278, 645, 1,130, 617, and 349 mOsmol/kg, respectively. Gastric evacuation of water-soluble materials from formulas containing sucrose, fructose, or glucose polymers was significantly slower than the gastric evacuation of the basic formula and the formula that contained lactose. The net fluid absorption from the small intestine was significantly greater from the basic and lactose-containing formulas when compared with sucrose, fructose, or glucose polymer-containing formulas. When the synthetic milk formulas were placed directly into the isolated jejunoileum in vivo, the formulas of higher osmolality (fructose, sucrose, and lactose) caused water flux into the intestine at 60 min, while digestion of the lactose formula reversed the water flux within 120 min. We conclude that the type of added sugar is a decisive factor in gastric evacuation, and that water flux into and out of the intestine is significantly affected by the osmolality and rate of digestion and absorption of the carbohydrate in the formula; these differences among sugars may play a significant role in the etiology of diarrhea.

Precocious increase of sucrase activity by carbohydrates in the small intestine of suckling rats. I. Significance of the stress effect of sugar-induced diarrhea

In this paper, we analyze the factors involved in the precocious increase of sucrase activity evoked by the early feeding of sucrose in suckling rats, and particularly, the role of diarrhea and stress in this phenomenon. Ten-day-old rats were removed from their mothers and gavage fed for 4 days at 3-h intervals either a basic low carbohydrate milk formula (10.8% fat, 8% protein, 1.4% carbohydrate; all by weight/volume) or basic low carbohydrate milk with: lactose (13%), fructose (13%), or Polycose (2%, 6%, or 13%); all formulas were isocaloric. Feeding the formula containing fructose or high (13%) Polycose led to diarrhea and evoked a concurrent increase of small intestinal sucrase activity. In further experiments, 11-day-old rats were fed the basic formula, the lactose (13%), the fructose (13%), and a sucrose (13%) formula for 8 h between 2 a.m. and 10 a.m. Also, 10-day-old rats were fed 0.5 ml of a solution of 5% mannitol in water while nursing with their mothers. The serum corticosterone levels were substantially increased within 8 h after the initiation of feedings with sucrose and fructose milks and the mannitol solution. The mannitol-fed rats also developed diarrhea within a day in association with a marked increase in sucrase activity. We conclude that a precocious increase of sucrase activity in the small intestine of suckling rats by dietary sugars is not caused by substrate induction, but is mainly due to the effect of stress. The stress is caused by diarrhea which is evoked by the feeding of indigestible and/or unabsorbable amounts of sugar.

Relation between dietary-induced increase of intestinal lactase activity and lactose digestion and absorption in adult rats

To study the relation between dietary-induced increase of intestinal lactase activity and lactose absorption, 11-wk-old rats were fed either a high-starch (70 cal%), low-fat (7 cal%) diet or a low-starch (5 cal%), high-fat (73 cal%) diet for 7 days. Food intake and body weight changes were similar in the two dietary groups. In the first experiment, lactose absorption was studied in vivo after oral administration of 600 mg lactose (10% solution in water with added [3H]PEG) to rats fasted for 16 h. Groups of rats were killed at time 0 and at 1-h intervals for the next 3 h. Lactase activity and lactose absorption were significantly higher (P less than 0.01) in the high-starch group than in the low-starch group. In the subsequent experiment, 9-wk-old rats were fed the two isocaloric diets for 3 days. By use of the everted sac technique, we have demonstrated a significantly higher absorption of monosaccharides from lactose in the high-starch diet group; also, glucose transport was higher in the high-starch diet-fed animals. When Tris, an inhibitor of lactase, was added into the mucosal fluid, absorption of lactose was abolished and no effect was seen on glucose absorption (in vivo and in vitro). In both experiments, significant linear regression was established between lactase activity and lactose absorption. Our results thus show that the increase in lactase activity, induced by feeding a high-starch diet to adult rats, is accompanied by an increased capacity to hydrolyze lactose and absorb the constituent monosaccharides.

Dietary induced increase of lactase activity in adult rats is independent of adrenals

Adult rats fed 10 days a low starch-high fat diet were either adrenalectomized or sham-operated and force-fed the same diet another 5 days; 14 h before sacrifice, some animals were force-fed a sucrose diet. Activity of lactase, sucrase and maltase was increased in adrenalectomized and sham-operated rats.

Dietary-induced increase in lactase activity and in immunoreactive lactase in adult rat jejunum

Adult rats that had been fed on a low-starch high-fat diet for 7 days were force-fed with either the same diet or isoenergetic diets containing 40% of energy as either sucrose or lactose. Within 12h, the increase in jejunal lactase activity in sucrose- and lactose-fed rats was accompanied by a corresponding increase in immunoreactive lactase protein.

Dietary-induced rapid decrease of microvillar carbohydrase activity in rat jejunoileum

Activities of several carbohydrases and peptidases were determined in proximal, middle, and distal thirds of the jejunoileum of female 16-wk-old rats that were fed a high-starch (70 cal%), low-fat (7 cal%) diet for 2 wk and also in rats that (after this introductory period) were fed an isocaloric low-starch (5 cal%), high-fat (73 cal%) diet for 1, 2, and 3 days. The body weight changes, food intake, amount of protein per intestinal segment, and rate of enterocyte migration were practically the same in all groups during these experimental periods. The decreased intake of starch was followed by a rapid decrease (40-80%) of carbohydrases (lactase, sucrase, maltase, and glucoamylase) within the first 24 h in total intestinal homogenates--and as studied in cryostat serial sections--in all regions of the jejunal villus-crypt columns, and mainly in proximal and middle segments. In contrast, the activities of leucylnaphthylamidase and L-phenylalanylglycine hydrolase exhibited little change except for a slight temporary decrease of activity on the 1st day in the proximal segment only (25-30%). Thus these data show that a decrease of starch content in an isocaloric diet evokes a rapid decrease in the activity of microvillar carbohydrases and that activity of these enzymes both in mature and immature enterocytes is capable of reacting to a change (decrease) of dietary carbohydrate content.

Different effect of starvation on activity of sucrase and lactase in rat jejunoileum

Activities of lactase and sucrase were determined in proximal, middle, and distal thirds of the jejunoileum of 15-wk-old male rats starved for 1, 2, and 3 days and in rats fed a high-sucrose diet for 24 h after 3 days of starvation. Sucrase activity (expressed per tissue protein or DNA as well as per intestinal segment) showed a progressive decrease during starvation in proximal and middle segments but not in the distal segment. Lactase activity expressed per tissue protein or DNA in all segments increased significantly. This was obviously due to the loss of tissue protein and DNA because total lactase activity per segment did not change. Refeeding the sucrose diet produced an increase of sucrase activity without influencing lactase activity. In serial tissue homogenate of jejunal villus-crypt columns prepared using cryostat sectioning, it was shown that, during starvation, activity of lactase (specific and total) increased in the upper and middle villus. Sucrase activity (specific and total) during starvation decreased and after refeeding increased in the lower and middle villus.

Thyroxin-evoked increase of sucrase activity in lower villus in the jejunum of adrenalectomized suckling rats

Intestinal sucrase activity, absent in the suckling rat, is evoked precociously by thyroid hormones. Since enterocytes migrate from crypt to villus tip, the question arises: at which level of the villus--crypt columns do the enterocytes respond with an increase of sucrase activity to thyroxin (T4)? Suckling rats (11 days old) were injected daily, subcutaneously, with T4 (2 micrograms/g BW/day). They were sacrificed 1, 2, and 3 days later. Sucrase activity was determined in homogenates of the entire jejunal wall and in serial homogenates of the villus-crypt columns using cryostat sectioning. Maximal increase of sucrase activity was seen after 3 days in the lower villus. Experiments were also done using rats adrenalectomized on day 10 to exclude the effect via precocious maturation of adrenal cortex. The same results were obtained. In conclusion, T4-evoked increase of sucrase activity occurs first in enterocytes that are nearest the villus-crypt junction.

Congenital mesoblastic nephroma

Neonatal renal neoplasms are rare: most are congenital mesoblastic nephroma. In the past this neoplasm has been confused with Wilms' tumor, which in part may account for some of the more favorable prognosis ascribed to Wilms' tumor in children less than 1 yr of age. Congenital mesoblastic nephroma is usually a benign tumor. The recommended treatment is surgical excision. This is a report of two cases of congenital mesoblastic nephroma in infants who were treated successfully by nephrectomy.

Time- and dose-dependency of intestinal lactase activity in adult rat on starch intake

Although it is generally accepted that lactase (beta-D-galactosidase, EC 3.2.1.23) activity is not influenced by intake of saccharides containing alpha-linkages, an effect of these carbohydrates on lactase activity was never thoroughly investigated. Activity of lactase and sucrose alpha-D-glucohydrolase, EC 3.2.1 48) was determined in proximal, middle and distal thirds of the jejunoileum of female, 12-week-old rats, fed for 2 weeks a low-starch (5 cal%), high-fat (73%) diet, and in rats, that after this introduction period were fed for 1, 2 and 3 days, an isocaloric middle-starch (40%), middle-fat (36%) diet or an isocaloric high-starch (70%), low-fat (7%) diet. During the entire experimental period, the body weight changes, food intake and the amount of protein per segment were practically the same in all three dietary groups. In all intestinal segments, increased intake of starch was followed by an increase of lactase and sucroase activity (both expressed as per tissue protein or per intestinal segment ) within the first day. The increase continued during the second day and leveled off during the third day. A highly significant linear correlation was found between the search content of the diets and the lactase activity in all three segments. A highly significant correlation was also established in all three segments between sucrase and lactase activities. These studies thus demonstrated a dose- and time-dependency between the intake of starch (a carbohydrate containing only alpha-linkages) and the activity of lactase, a neutral beta-galactosidase in adult rats.

Increased activity of rat intestinal lactase due to increased intake of alpha-saccharides (starch, sucrose) in isocaloric diets

The adaptability of intestinal microvillar alpha-disaccharidases to the variation of alpha-saccharide content in the diets is well established, but the influence of these sugars on the activity of microvillar lactase (neutral beta-galactosidase) has heretofore been considered negligible or non-existing. In two experiments rats were fed isocaloric diets where the carbohydrate (starch or sucrose) content versus fat content was varied. (High carbohydrate diets: 71% of calories as carbohydrate and 5% of calories as fat; low carbohydrate diets: 6 and 73% calories, respectively). Experiment 1: male and female rats had access to experimental diets only from day 12 postnatally and were killed at age 56 days. Experiment 2: male rats were fed experimental diets starting on day 73 postnatally and killed 3, 7, 14 and 28 days later. Rats fed the high carbohydrate diets exhibited a significant increase in activity (specific and total per segment) of lactase in all three intestinal segments compared to rats fed the low carbohydrate diets. Changes in the activity of sucrase and maltase paralleled those of lactase activity. These experiments have thus demonstrated clearly the influence of variation in alpha-saccharide content in the diet upon lactase activity. Further experiments are needed to determine the active principle of this dietary adaptation.