Imaging and video of late preterm delivery by midline laparotomy due to incarcerated uterus: A case report and literature review of a rare but morbid condition.

Incarcerated gravid uterus (IGU) is a rare and serious obstetric complication. IGU is defined as the entrapment of the gravid uterus between the pubic symphysis and the sacral promontory. The incidence of IGU is 1 in 3000-10 000 cases. IGU is associated with significant obstetric complications, including preterm labor, intrauterine fetal death, growth restriction, renal failure, uterine ischemia/rupture and thrombosis. Here, we present the case of a primigravida with urinary retention at 14 weeks. On transabdominal ultrasound at 19+5/7 weeks the cervix was difficult to visualize, and the anterior uterine wall appeared thickened. The bladder was elongated superior to the uterus and the placenta was low-lying. Initially the patient was managed with intermittent self-catheterization, and subsequently indwelling catheterization was required from 22 weeks. At 30 weeks, the patient was transferred to a tertiary center and magnetic resonance imaging (MRI) was preformed due to challenging visualization of the cervix on ultrasound and the patient's continued symptoms of constipation and recurrent urinary infections. The MRI found a retroflexed gravid uterus, with vagina and endocervix displaced anteriorly and compressed by the gravid uterus. The findings were consistent with an incarcerated uterus. The patient subsequently had positive urinary cultures for Pseudomonas and rising creatinine. Given the obstructive uropathy and associated morbidity and mortality, a plan for elective pre-term delivery at 33+6/7 weeks was made. Delivery was by midline laparotomy, normal anatomy was restored after manual evacuation of the fundus from below the sacral promontory, and an uncomplicated lower segment transverse uterine cesarean section was performed.

Assessment of binding of L-cystine and L-lysine by rat renal brush-border membranes.

Cystine and lysine bind to isolated rat renal brush-border vesicles. Three methods to determine the extent of amino acid binding to the membranes have been compared, one relying on the osmotic reactivity of the vesicle, a second by trichloroacetic acid precipitation of membrane-bound material and a third by initial rate analysis. For cystine, all methods yield comparable results at early time points, indicating the trichloroacetic acid method is a simple and valuable tool for binding estimation under initial-rate or near initial-rate conditions. For lysine, initial rate analysis and osmotic perturbation are the methods of choice since lysine co-precipitates with trichloroacetic acid.

L-cystine transport by papain-treated rat renal brush-border membrane vesicles.

In papain-treated rat renal brush-border membrane vesicles, cystine uptake was enhanced under sodium gradient conditions. This effect was not observed when sodium was equilibrated across the vesicle membrane or when sodium was completely absent from the incubation medium. The increased rate of cystine uptake occurred within the first two minutes of incubation and coincided with the period of increased flux of sodium known to occur after papain treatment. Under sodium gradient conditions, the Vmax of cystine uptake by treated vesicles was 65% greater while the Km was 25% lower than the value observed in untreated membranes. The increased cystine uptake after papain treatment occurred when medium cystine was in the electroneutral form. In the absence of a sodium gradient, cystine uptake by control membranes was insensitive to changes in membrane potential and this was unaltered after papain treatment. Exposure of the membranes to papain also resulted in a profound decrease in cystine binding which occurs in native membranes incubated with cystine. The fact that cystine uptake is unchanged under sodium equilibration and even enhanced under sodium gradient conditions suggests that the component of cystine binding is not essential for cystine transport and may represent non-specific binding to membrane proteins.

Absence of a role of gamma-glutamyl transpeptidase in the transport of amino acids by rat renal brushborder membrane vesicles.

The role of the enzyme, gamma-glutamyl transpeptidase on the uptake of amino acids by the brushborder membrane of the rat proximal tubule was examined by inhibiting it with AT-125 (L-[alpha S, 5S]-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid). AT-125 inhibited 98% of the activity of gamma-glutamyl transpeptidase when incubated for 20 min at 37 degrees C with rat brushborder membrane vesicles. AT-125 given to rats in vivo inhibited 90% of the activity of gamma-glutamyl transpeptidase in subsequently isolated brushborder membrane vesicles from these animals. AT-125 inhibition of gamma-glutamyl transpeptidase both in vivo and in vitro had no effect on the brushborder membrane uptake of cystine. Similarly, there was no effect of gamma-glutamyl transpeptidase inhibition by AT-125 on glutamine, proline, glycine, methionine, leucine or lysine uptake by brushborder membrane vesicles. Furthermore, the uptake of cystine by isolated rat renal cortical tubule fragments, in which the complete gamma-glutamyl cycle is present, was unaffected by AT-125 inhibition of gamma-glutamyl transpeptidase. Therefore, in the two model systems studied, gamma-glutamyl transpeptidase did not appear to play a role in the transport of amino acids by the renal brushborder membrane.

The effect of papain upon proline and sodium transport of rat renal brush-border membrane vesicles.

Treatment of renal brush-border membrane vesicles with papain resulted in the removal of the activity of maltase, gamma-glutamyl transpeptidase and leucine aminopeptidase by 85, 50 and 75%, respectively. Stripping of these membrane enzyme activities constituted about 2% of the total membrane proteins and resulted in a widespread diminution in the ability of a variety of amino acids and sugars to be taken up by the membrane vesicles which remained osmotically responsive. Kinetic analysis of the uptake of proline, which was shown previously to be transported by both sodium-dependent and sodium-independent systems, revealed that the Vmax for the sodium-dependent system and Km for the sodium-independent system were halved, but other parameters were not affected indicating that the papain treatment altered sodium-gradient-stimulated entry and the affinity of the sodium-gradient-independent system for proline. Experiments on sodium entry and efflux demonstrate a marked enhancement of flux, so that equilibration of the sodium gradient occurred about 5-times more rapidly than in untreated vesicles. This occurred without any change in the osmotic properties of the vesicle with regard to sodium or amino acid uptake. Studies of fluorescence polarization suggest that incubation with papain does not alter the lipid domains of the membrane.

The effect of azaserine upon the proline and methyl alpha-D-glucoside transport systems of rat renal brush-border membranes.

An inhibitory effect of azaserine on Na+ dependent proline and methyl alpha-D-glucoside transport of the rat renal brush-border membrane vesicles has been demonstrated. The inhibitory effects of azaserine were not the results of the drug disrupting the membrane vesicles as shown in osmolarity studies, nor did it affect the transport systems' affinities for Na+. Azaserine acts as a non-competitive inhibitor for the proline transport system in renal brush-border membranes by lowering 37% and 27% in the Vmax1 and Vmax2, respectively, when compared to that of control proline transport system. Azaserine had no effect upon the two Km values for proline uptake. Azaserine inhibition of methyl alpha-D-glucoside uptake by vesicles in the presence of 7.2 mM azaserine at 22 degrees C resulted in 66% increase in Km1 value and 44% decrease in Vmax1 as compared to that of control vesicles. There was no detectable effect upon the Km2 and Vmax2 of the methyl alpha-D-glucoside transport system. No effect of the drug was observed when sodium was equilibrated across the membrane, indicating that azaserine altered the driving force exerted by a sodium gradient. Azaserine only slightly affected the relative contribution of the two Km systems to total proline uptake. Contrary to the observed effect of azaserine upon the proline transport system, azaserine exerted a distinct effect upon the relative contribution to total uptake by the two Km systems in the low methyl alpha-D-glucoside concentration range. In the presence of 7.2 mM azaserine, the low-affinity, high-Km transport system becomes the major contributor to total methyl alpha-D-glucoside uptake by isolated renal brush-border vesicles.

The effect on amino acid transport of trypsin treatment of rat renal brush border membranes.

Trypsin treatment of isolated rat renal brush border membrane vesicles which preferentially releases L-leucine aminopeptidase (EC 3.4.11.2) decreases their ability to take up a variety of amino acids under Na+ -gradient conditions. Such treatment did not alter the osmotic properties of the vesicles nor affect their fragility. A linear correlation could be demonstrated between the L-leucine aminopeptidase activity of the membranes and the initial rate of uptake of L-leucine and L-proline. Velocity of uptake-concentration dependence studies with these substrates indicate that the major effect of trypsinization is to decrease the maximum velocity (Vmax1) of the low-Km high-affinity system with little effect on the Vmax2 of the high-Km low-affinity transport process and no effect on the apparent Michaelis constants of either. Although the data indicate that L-leucine aminopeptidase activity and uptake of l-leucine and L-proline are affected in parallel, they should not be construed to imply a role of the enzyme in the transport process, especially in view of the global decrease in the uptake of various amino acids and sugars.