cron-web.org

[A1CR]

http://en.wikipedia.org/wiki/Maltase is the enzyme for
http://en.wikipedia.org/wiki/Maltose and
http://en.wikipedia.org/wiki/Special:Search?http://en.wikipedia.org/wiki/Sucrase

digests http://en.wikipedia.org/wiki/Sucrose whereas
http://en.wikipedia.org/wiki/Lactase appears to be the
enzyme for milk
protein lactose. The paper below (2) describes what may
occur when, with
respect to intestinal sugars digesting enzymes, rabbits are
CRed. Finding
little difference with respect to intestinal function
appears to have been
demonstrated in (2).

First, Medline now has the (1):

Baur JA, Pearson KJ, Price NL, Jamieson HA, Lerin C, Kalra
A, Prabhu VV,
Allard JS, Lopez-Lluch G, Lewis K, Pistell PJ, Poosala S,
Becker KG, Boss O,
Gwinn D, Wang M, Ramaswamy S, Fishbein KW, Spencer RG,
Lakatta EG, Le
Couteur D, Shaw RJ, Navas P, Puigserver P, Ingram DK, de
Cabo R, Sinclair
DA.
Resveratrol improves health and survival of mice on a
high-calorie diet.
Nature. 2006 Nov 1; [Epub ahead of print]
PMID: 17086191

Islam S, Mitra AK, Chowdhury AK, Alam NH.
Intestinal enzymes during malnutrition & infection in rabbits.
Indian J Med Res. 2006 Sep;124(3):313-8.
PMID: 17085835

BACKGROUND & OBJECTIVES: Malnutrition plays an important
role in the
intestinal absorption of nutrients. However, reports are not
consistent
whether intestinal enzymes are decreased in the presence of
malnutrition. It
is also not clear whether simultaneous presence of
malnutrition and
infection adds to the problem of malabsorption of nutrients.
The aim of the
present study was to determine intestinal functions in terms of
concentrations of disaccharidase enzymes during diarrhoea
and protein energy
malnutrition. METHODS: Concentrations of three
disaccharidase enzymes,
namely maltase, sucrase and lactase were measured in nine
energy-restricted
and five control rabbits during diarrhoea induced by rabbit
diarrhoeagenic
Escherichia coli (RDEC-1). Malnutrition was achieved in the
rabbit model by
feeding the animals for 30 days with half the amount of food
fed to
well-nourished control rabbits. Both the energy-restricted
and the control
groups were challenged by RDEC-1. Diarrhoea occurred on day
1-7 after
administration of the strain. After onset of diarrhoea, both
groups of
rabbits were sacrificed and their intestinal mucosa was
examined to
determine the concentration of lactase, maltase and sucrase.
RESULTS: The
energy-restricted animals and controls did not differ
significantly for
concentrations (units/mg proteins) of lactase (0.65 +/- 0.28
vs 0.56 +/-
0.17 ), maltase (6.20 +/- 2.70 vs 6.47 +/- 1.90) and sucrase
(5.42 +/- 2.30
vs 5.13 +/- 1.40) measured during acute infectious
diarrhoea. INTERPRETATION
& CONCLUSION: The results suggested that the enzymatic
functions of the
intestinal brush border were not statistically different
during diarrhoea
among malnourished rabbits compared with their
well-nourished counterparts.

Table. Composition of rabbit's diet
=================================================
Ingredients (g/kg)---Constituents (%)---Additives (quantity/kg)
=============================================
Wheat 320 Protein 15-17 Vitamin A 6000 µl
Wheat bran 280 Fat 2.5-3.5 Vitamin D3 1500 µl
Oat 100 Fibre 8.0-10.0 Vitamin E 30 mg
Grean gram (whole) mug 80 Crude ash 6 Copper 30 mg
Gram (Chola) 80 Gross energy 4.0 kcal/g - -
Soybean meal-44 40 - - - -
Til oil cake 60 - - - -
Molasses 10 - - - -
Salt 10 - - - -

Results
After challenging with RDEC-1 infection,
4 controls died leaving 5 controls and 9 test rabbits
for the entire analysis. The mean calorie intake per
day was signficantly higher in the control group
compared to the test group of rabbits (591.7±34.4
kcal vs. 294.2±13.6 kcal, P <0.001). The control
group of rabbits gained 46 per cent of body weight
whereas the test group (energy-restricted) gained
about 14 per cent of body weight after 30 days
of controlled feeding (P <0.001) (Fig.). After
challenge with RDEC-1 the control group lost
10 per cent of weight and the energy-restricted
group lost 2 per cent of weight at the end of 42
days (P <0.001). The absolute body weights (mean
± SD) between the control and the test groups did
not differ at baseline (860.6±47.9 g vs 835.1 ±
60.8 g); however, the control group had
significantly higher body weights compared to the
test group after 30 days of feeding (1256.4±69.9g
vs 952.0±69.3 g, P=0.001).

Concentrations of lactase, maltase and sucrase
in the energy-restricted group were 0.65±0.28, 6.20
± 2.7 and 5.42±2.3 IU/mg protein respectively, and
those in the control group were 0.56±0.17, 6.47 ±
1.9, and 5.13±1.4 IU/mg protein respectively. There
were no significant differences in the concentration
of any of these enzymes during diarrhoea between
the two groups.

Discussion
Results of our study confirmed that food
deprivation using the energy-restricted diet could
produce a malnourished rabbit model for the study,
and concentrations of small intestinal brush border
enzymes did not differ between the energy-restricted
and control group of rabbits.

In this study, animals were challenged with
RDEC-1 to produce diarrhoea. The RDEC-1 is a
serogroup 015 Escherichia coli that has pili and
surface polysaccharide. The bacterium is not invasive
and does not synthesize enterotoxins. Both pili and
surface polysaccharide make the bacteria adhere to
the membraneous (M) cells of lymphoid follicle
epithelium of ileal Peyer's patches within a few hours
of inoculation of rabbits. By 3-6 days, microcolonies
of the bacteria adhere to the ileal, cecal, and colonic
mucosa and diarrhoea occurs21.

The gastrointestinal flora is altered in
malnourished state, and protein energy malnutrition
is associated with various degrees of intestinal
malabsorption. These changes are believed to
predispose such individuals to repeated enteric
infections23. Stanfield and coworkers12 observed
severe alterations, either flat or short and thick villi
in the majority of children with kwashiorkor. In these
children, no significant improvement in the mucosal
architecture was noted even at a follow up one year
later.
In protein energy malnutrition, intestinal villus
heights are typically decreased because of the
significant decrease in the number of cells as well as
decrease in enterocyte proliferation and migration
rates along the crypt-villus axis6. This led to
reductions in total surface area and mucosal mass.
Malnutrition is typically associated with significant
reductions of body weight, mucosal mass, intestinal
protein content, and total intestinal surface area.
These effects are closely associated with the loss of
luminal nutrition24.

Reductions in the activities of intestinal
disaccharidases have been well documented during
malnutrition and infection both in animals and in
humans. An earlier study observed reduction in the
disaccharidases activities in jejunal biopsies of
24 malnourished children with gastrointestinal
symptoms7. In a clinical trial, Mehra and
coworkers25 have described significant reduction in
the lactase activity in subjects with 3rd and 4th degree
of malnutrition (P <0.05 and P <0.005,
respectively), but maltase activity was significantly
reduced only in subjects with 4th degree of
malnutrition (P <0.01).
To our knowledge, ours is probably the first
report that compared intestinal disaccharidase
concentrations in malnourished and well-nourished
rabbits infected with RDEC-1. It is not possible to
develop an experimental malnutrition model which
would exactly represent human beings with different
grades of malnutrition. However, in human studies
it is difficult to demonstrate the effects of
malnutrition per se because a number of other factors
(including food intolerance, other diseases and
infections, antibiotic use, etc.) could alter the
intestinal morphology and thus confound the results.
The rabbit provides an excellent animal model for
the study of the human cases of diarrhoea due to
enteropathogenic serogroup of E. coli, in which the
human gut histopathology is similar to that of strain
RDEC-1 diarrhoea in the rabbit21.
An earlier study observed similar activity of
intestinal mucosal disaccharidases in growth retarded
(malnourished) and control rats but without
infection26, while another had observed reduced
specific activities of lactase, sucrase and maltase in
prenatally malnourished rats27. But the activities of
these enzymes were higher in other malnourished
groups (postnatal, post-weaning and adulthood) as
compared to corresponding controls27. However,
none of these studies examined the role of
malnutrition during infection.
Our study had some limitations. In our study,
RDEC-1 was injected on day 30 of the study, and
rabbits were sacrificed after they developed
diarrhoea. It would have been better to have a
standard time period after administration of
RDEC-1 infection before sacrifice and
determination of disaccharidase activity. The
variability in time of estimation of disaccharidase
activity may be one reason why a significant
difference was not found between the two groups.
However, we should also recognize the fact that the
time of bacterial colonization and appearance of
diarrhoea is variable. Another weakness of the study
was relatively small sample size. The study could
have been more powerful if it included a second
control group of animals that did not have RDEC-1
infection, in order to know the enzyme activity in
the normal animals.

In conclusion, our study suggests that the
intestinal enzyme concentrations (lactase, maltase,
and sucrase) remain similar during dirrhoea in
energy-restricted animals and controls. Further
controlled studies with larger sample sizes are needed
to demonstrate the effect of malnutrition and
infection on intestinal enzyme functions.