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Biomedical subjects

S R Khan

Publications and source records attributed to S R Khan.

At least 109 records · Page 6Linked to original sources
PubMed1988

Presence of calcium oxalate crystals in the mammalian thyroid gland.

Birefringent crystals of calcium oxalate have been previously identified in the colloid of human thyroid glands. We found such crystals in 19/20 adult thyroids at autopsy, in 4/20 infants at autopsy, and, using frozen sections, in 19/20 thyroids partially or totally removed at surgery. These crystals were soluble in hydrochloric acid, insoluble in acetic acid, and contained only calcium by energy dispersive X-ray microanalysis, confirming their calcium oxalate character. Similar crystals were found in equine and ovine thyroids.

Birefringence↗
PubMed1987

Crystal-matrix relationships in experimentally induced urinary calcium oxalate monohydrate crystals, an ultrastructural study.

Calcium oxalate monohydrate crystalluria was experimentally induced in male rats by administration of ethylene glycol. The crystalluria particles were separated by filtration and studied by scanning and transmission electron microscopy. They were associated with cellular degradation products. Organic material was present both on the surfaces of crystalluria particles as well as within them and was organized in radial striations and concentric laminations. It is proposed that crystal nuclei were formed by heterogeneous nucleation. These nuclei then adsorbed organic material and aggregated. The organic material polymerized resulting in the formation of a crystal-matrix unit which then grew and incorporated more organic material during the crystal growth.

Animals↗
PubMed1987

Urolithogenesis of mixed foreign body stones.

Urine of male Sprague-Dawley rats was supersaturated for struvite and often contained struvite crystals. Ethylene glycol administration to these rats resulted in elevation of urinary oxalate and calcium oxalate supersaturation, and induced calcium oxalate crystalluria. Implantation of foreign bodies in their urinary bladders and changing their urinary ambient conditions by administering ethylene glycol for two weeks at two week intervals resulted in the formation of urinary stones of mixed composition containing calcium oxalate and struvite. Crystal-onto-crystal epitaxy did not appear to play any role in the development of these stones.

Animals↗
PubMed1987

Regulation of serum sodium in dehydrated and orally rehydrated infants. Influence of age and of purging rates.

We have examined the control of serum sodium concentration (S-Na) in 60 male infants with acute diarrheal disease, moderate dehydration, but without the presence of fever, vomiting or other conditions. The infants were studied on admission and during oral rehydration therapy (ORT). We examined the effect of rapid reduction of the purging rate on the control of S-Na by adding pulverized rice and pulses (dal moong) to the rehydration solution. On admission S-Na was significantly inversely related to age. This correlation could not only be attributed to difference in stool sodium losses. Changes in S-Na and urinary K/Na ratio during oral rehydration therapy (ORT), were analyzed separately in infants below and above 4 month of age. During the first six hours of ORT, there was an increase in S-Na in all groups. During the following 18 hours, S-Na tended to normalize around 138 mmol/l. Normalization occurred faster if purging rate was reduced. In all groups urinary K/Na ratio (index of aldosterone production and, inversely, of sodium balance), was high at admission and fell during ORT. In the youngest infants (below 4 month of age) the fall was significantly more pronounced if the purging was reduced. We conclude that it is important to consider age when prescribing ORT. The capacity to correct disturbances in S-Na becomes more efficient during maintenance stage of ORT. Correction of S-Na and sodium balance is enhanced by rapid reduction of abnormal intestinal losses.

Acute Disease↗
PubMed1987

The benefits of the very early introduction of powdered rice and dried edible seeds (Dal moong) in the oral rehydration solution during the treatment of acute infectious diarrhoea of infancy.

We have examined whether the addition of powdered rice and pulses (Dal moong) to oral rehydration solution will decrease the purging rate and thereby increase the efficacy of the oral rehydration therapy. The study was carried out on 60 male infants, with acute watery diarrhoea, moderate dehydration but without fever, vomiting, or other conditions like septicaemia and meningitis. The infants were treated with either the standard WHO oral rehydration salt solution (ORS) or with a modified solution where glucose was removed and powdered rice and Dal moong were added. We found that the infants receiving ORS with powdered rice and Dal moong had significantly lower fluid losses in the stools, a significant and more rapid weight gain, and needed significantly less fluid than the infants receiving ORS only.

Acute Disease↗
PubMed1987

Role of scanning electron microscopy and x-ray microanalysis in the identification of urinary crystals.

Urinary crystals can be identified by using analytical electron microscopic techniques of scanning electron microscopy and energy dispersive x-ray microanalysis. Crystal habit can be recognised by scanning electron microscopy and their chemical nature by elemental analysis. With a conventional detector the lightest element that can routinely be detected is sodium, but with a windowless or thin window detector even carbon can be detected. Thus almost all the commonly occurring urinary crystals including uric acid can be analysed by energy dispersive x-ray microanalysis.

Calcium↗
PubMed1986

Morphology of urinary stone particles resulting from ESWL treatment.

Fragments of urinary stones resulting from extracorporeal shock wave lithotripsy were examined by light and scanning electron microscopy. Calcium oxalate monohydrate and uric acid stone fragments were homogeneous and regular whereas struvite stone fragments were irregular in shape. Examination of the fractured surfaces revealed that the process of stone fragmentation involved fracture and cleavage of the crystals at some places and their separation from each other at others. In stones whose crystals are organised in layers, for instance calcium oxalate monohydrate and uric acid, crystalline layers separated along the concentric laminations. In struvite stones, which are an agglomeration of struvite and calcium phosphate crystals, major fragmentation occurred along the crystalline interfaces.

Calcium Oxalate↗
PubMed1986

Identification of urinary stone and sediment crystals by scanning electron microscopy and x-ray microanalysis.

A procedure based on scanning electron microscopic techniques is described for the identification of crystals in urinary sediments and stones. The crystals are identified by their morphology and elemental composition using scanning electron microscopy and x-ray microanalysis. The procedure has a number of advantages over conventional methods. It is easy to use. It is non-destructive so that both the exterior and interior of the same stone can be separately analyzed. It is the only technique in which information about spatial relationships between various crystals in a stone can be obtained easily. Scanning electron microscopic techniques can detect minor components, and analysis of a wide variety of materials ranging from amorphous substances to microcrystals to macroscopic stones is possible.

Animals↗
PubMed1986

Histochemistry of colloidal iron stained crystal associated material in urinary stones and experimentally induced intrarenal deposits in rats.

Organic material associated with the calcium oxalate crystals in urinary stones and experimentally induced nephrolithiasis was stained with colloidal iron and analysed by energy dispersive x-ray microanalysis using standard techniques. Iron was positively identified in the stained specimens indicating that some of the organic material is an acidic mucosubstance. The results also indicate that some of the organic material of urinary stones may originate in the kidneys.

Animals↗
PubMed1985

Developmental morphology of calcium oxalate foreign body stones in rats.

Calcium oxalate bladder stones were induced in male rats by implanting plastic foreign bodies and by adding ethylene glycol to their drinking water. The foreign body surface was first coated with cellular debris and some amorphous material. Encrustation with crystals of calcium oxalate started on the third day of implantation. Within 2 weeks the entire surface of a foreign body was covered with crystals and some noncrystalline material. Calcium oxalate monohydrate crystals consisted of platelike crystallites arranged in hemispherulitic or spherulitic habit. Calcium oxalate dihydrate crystals wee basically dipyramidal, a majority of them showing interpenetrant twinning. The stone grew by confluent crystal growth and crystal aggregation. A transformation of calcium oxalate monohydrate crystals to calcium oxalate dihydrate also occurred. The matrix consisting of cellular debris and urinary macromolecules was universally distributed in the stone including the inside of crystal bodies.

Animals↗
PubMed1985

Scanning electron microscopy, x-ray diffraction, and electron microprobe analysis of calcific deposits on intrauterine contraceptive devices.

Deposits found intrauterine contraceptive devices (IUDs) were studied by scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray microanalysis. All seven devices, including five plastic and two copper IUDs, were coated with a crust containing cellular, acellular, and fibrillar material. The cellular material was composed of erythrocytes, leukocytes, cells of epithelial origin, sperm, and bacteria. Some of the bacteria were filamentous, with acute-angle branching. The fibrillar material appeared to be fibrin. Most of the acellular material was amorphous; calcite was identified by x-ray diffraction, and x-ray microanalysis showed only calcium. Some of the acellular material, particularly that on the IUD side of the crust, was organized in spherulitic crystals and was identified as calcium phosphate by x-ray microanalysis. The crust was joined to the IUD surface by a layer of fibrillar and amorphous material. It is suggested that the initial event in the formation of calcific deposits on IUD surfaces is the deposition of an amorphous and fibrillar layer. Various types of cells present in the endometrial environment adhere to this layer and then calcify. Thus, the deposition of calcific material on the IUDs is a calcification phenomenon, not unlike the formation of plaque on teeth. Hum Pathol 16:732-738, 1985.

Calcium↗
PubMed1985

Scanning electron microscopy as an analytical tool for the study of calcified intrauterine contraceptive devices.

Within the endometrial cavity intrauterine contraceptive devices (IUDs) become encrusted with cellular, acellular, and fibrillar substances. Scanning electron microscopy was used to study the crust. Cellular material consisted mainly of blood cells and various types of bacteria. The fibrillar material appeared to be fibrin which was omnipresent in the crust and formed a thin layer immediately over the IUD surface. X-ray microanalysis of the acellular component of the crust revealed the presence of calcium. No other major peaks were identified. Near the IUD surface characteristic calcium phosphate crystals were present. Their microanalysis showed peaks for calcium and phosphorus. X-ray diffraction of the crust however, showed it to contain only calcite. It is through the use of scanning electron microscopy that calcium phosphate has been detected in the IUD crust and a fibrillar layer has been visualized on the IUD surface. This study further demonstrates the effectiveness of SEM analytical techniques in the area of biomedical research.

Adult↗
PubMed1985

Calcium oxalate urolithiasis in the rat: is it a model for human stone disease? A review of recent literature.

Calcium oxalate stone disease is the most common human urinary stone disease in the Western Hemisphere. To understand different aspects of the disease, calcium oxalate urolithiasis in the rat is used as a model. Spontaneous calcium oxalate urolithiasis is very rare in rats. Thus the disease is experimentally induced and the rats are generally made hyperoxaluric either by administration of excess oxalate, exposure to the toxin ethylene glycol, or various nutritional manipulations. All the experimental models show renal injury associated with crystal deposition. Calcium oxalate crystals are in most cases intraluminal in renal tubules and often attached to the basal lamina of the denuded epithelium. Rat renal papillary tips and fornices appear to be the preferential sites for the deposition of large calcium oxalate calculi. Where urinary supersaturation of calcium oxalate has been studied the crystal forming rat urines are shown to have higher urinary supersaturation of calcium oxalate than their controls. Oxalate metabolism in the rat is nearly identical to that in humans. Thus, in a number of respects, experimental calcium oxalate urolithiasis in the rat is similar to calcium oxalate stone disease in man.

Animals↗
PubMed1984

Relationship between experimentally induced crystalluria and relative supersaturation of various stone salts in rats.

Calcium oxalate crystalluria was induced in laboratory rats by subcutaneous implantation of potassium oxalate containing mini-osmotic pumps in their intercapsular region. Concentrations of major urinary ions were measured and urinary supersaturations of various urinary salts were calculated using a computer programme. The urines of experimental animals that received oxalate had calcium oxalate crystals and higher supersaturations for calcium oxalate compared to their controls. Oxalate levels of the urines of experimental animals were higher than their controls and this increase was proportional to the increase in urinary supersaturation of calcium oxalate. No significant difference was found in the calcium levels of urines from experimental and control animals.

Animals↗
PubMed1984

Renal papillary changes in patient with calcium oxalate lithiasis.

We report the case of a white woman with bilateral renal calculi that were removed by bilateral nephrolithotomies. The morphology of renal tubular stones and the changes in papillary tissue were studied by light microscopy and scanning and transmission electron microscopy. The stones were made of calcium oxalate and were intratubular. Large calcium phosphate deposits were present in the interstitium. There was a marked interstitial fibrosis and tubular epithelial hyperplasia.

Calcium Oxalate↗
PubMed1984

Crystal retention by injured urothelium of the rat urinary bladder.

Injuries caused by hydrochloric acid or Triton X 100 application to the rat bladder urothelium, and the effects on calcium oxalate crystal retention, were examined by light and scanning electron microscopy. Damage due to either compound resulted in desquamation of urothelial cells. The crystals appeared to be retained by a fibrillar material, some of which was identified as fibrin. Heparin treatment of injured urothelium was found to prevent crystal retention.

Adhesiveness↗
PubMed1984

Microstructure of decalcified human calcium oxalate urinary stones.

Human urinary stone fragments and sections were decalcified in ethylenediaminetetraacetic acid solution after embedding in 1% agar. These decalcified embedded stone specimens were then processed for scanning electron microscopy. After critical point drying the agar was removed and EDTA-insoluble stone residue was studied by scanning electron microscopy. This residue representing part of the stone matrix kept the original shape of the stone and was basically made of fibrous material. The fibers appeared to be arranged in matted sheets that were present as concentric laminations. In case of calcium oxalate dihydrate stones these fibrous sheets were also arranged as peripheral layers running parallel to the pyramidal faces of large calcium oxalate dihydrate crystals. In decalcified stones, crystals were represented by crystal ghosts. Often some vesicular material was present embedded in the fibrous sheets.

Calcium Oxalate↗