Pulmonary nodule characterization: a comparison of conventional with quantitative and visual semi-quantitative analyses using contrast enhancement maps

PURPOSE

To determine whether conventional nodule densitometry or analysis based on contrast enhancement maps of indeterminate lung nodules imaged with contrast-enhanced CT can distinguish benign from malignant lung nodules.

MATERIALS AND METHOD

Thin section, contrast-enhanced CT (baseline, and post-contrast series acquired at 45, 90,180, and 360 s) was performed on 29 patients with indeterminate lung nodules (14 benign, 15 malignant). A thoracic radiologist identified the boundary of each nodule using semi-automated contouring to form a 3D region-of-interest (ROI) on each image series. The post-contrast series having the maximum mean enhancement was then volumetrically registered to the baseline series. The two series were subtracted volumetrically and the subtracted voxels were quantized into seven color-coded bins, forming a contrast enhancement map (CEM). Conventional nodule densitometry was performed to obtain the maximum difference in mean enhancement values for each nodule from a circular ROI. Three thoracic radiologists performed visual semi-quantitative analysis of each nodule, scoring each map for: (a) magnitude and (b) heterogeneity of enhancement throughout the entire volume of the nodule on a five-point scale. Receiver operator characteristic (ROC) analysis was conducted on these features to evaluate their diagnostic efficacy. Finally, 14 quantitative texture features were calculated for each map. A statistical analysis was performed to combine the 14 texture features to a single factor. ROC analysis of the derived aggregate factor was done as an indicator of malignancy. All features were analyzed for differences between benign and malignant nodules.

RESULTS

Using 15 HU as a threshold, 93% (14/15) of malignant and 79% (11/14) of benign nodules demonstrated enhancement. The ROC curve when higher values of enhancement indicate malignancy was generated and area under the curve (AUC) was 0.76. The visually scored magnitude of enhancement was found to be less effective in distinguishing malignant from benign lesions, with an average AUC of 0.62. The visually scored pattern of enhancement was found to be more effective with an average AUC of 0.79. From the statistical analysis performed to combine the texture features to a single factor, the area under the ROC curve was 0.84.

CONCLUSION

The present study suggests that visual semi-quantitative and quantitative characterization of contrast enhancement patterns may potentially enhance the discrimination between benign and malignant nodules. Further studies and correlation with pathologic material will be important to better understand the potential interplay between CT enhancement features, host stromal elements, and neovascularity that may contribute to these patterns.

Computer aided characterization of the solitary pulmonary nodule using volumetric and contrast enhancement features

RATIONALE AND OBJECTIVES

To investigate the utility of a computer-aided diagnosis (CAD) in the task of differentiating malignant nodules from benign nodules based on quantitative features extracted from volumetric thin section CT image data acquired before and after the injection of contrast media.

MATERIALS AND METHODS

35 volumetric CT datasets of solitary pulmonary nodules (SPN) with proven diagnoses (19 malignant/16 benign) were contoured by a thoracic radiologist. All studies had at least a baseline series obtained without contrast media and at least one series following an intravenous contrast injection at 45, 90, 180, and 360 seconds. Two separate contours were created for each nodule: one including only the solid portion and another including the ground-glass component, if any, of the nodule. For each contour 31 features were calculated that measured the attenuation, shape, and enhancement of the nodule due to the injection of contrast. These features were input into a feature selection step and three different classifiers to determine if the diagnosis could be predicted from the resulting feature vector. In addition, observer input was introduced to two of the classifiers as an a priori probability of malignancy and the resulting performance was compared. Training and testing was conducted in a resubstitution and leave-one-out fashion and performance was evaluated using ROC analysis.

RESULTS

In a leave-one-out testing methodology, the classifiers achieved areas under the ROC curves AZ that ranged from 0.69 to 0.92. A classifier based on logistic regression performed the best with an AZ of 0.92 while a classifier based on quadratic discriminant analysis performed the poorest (AZ, 0.69). The AZ increased when using a priori observer input in most cases reaching a maximum of 0.95.

CONCLUSION

Based on this initial work with a limited number of nodules in our dataset, it appears that CAD using volumetric and contrast-enhanced data has the potential to assist radiologists in the task of differentiating solitary pulmonary nodules and in the management of these patients. Further studies with an increased number of patients are required to validate these results.

Tuberculosis patient adherence to direct observation: results of a social study in Pakistan

A randomized controlled trial was carried out in Pakistan in 1999 to establish the effectiveness of the direct observation component of DOTS programmes. It found no significant differences in cure rates for patients directly observed by health facility workers, community health workers or by family members, as compared with the control group who had self-administered treatment. This paper reports on the social studies which were carried out during and after this trial, to explain these results. They consisted of a survey of all patients (64% response rate); in-depth interviews with a smaller sample of different types of patients; and focus group discussions with patients and providers. One finding was that of the 32 in-depth interview patients, 13 (mainly from the health facility observation group) failed to comply with their allocated DOT approach during the trial, citing the inconvenience of the method of observation. Another finding was that while patients found the overall TB care approach efficient and economical in general, they faced numerous barriers to regular attendance for the direct observation of drug-taking (most especially, time, travel costs, ill health and need to pursue their occupation). This may be one of the reasons why there was no overall benefit from direct observation in the trial. Provider attitudes were also poor: health facility workers expressed cynical and uncaring views; community health workers were more positive, but still arranged direct observation to suit their, rather than patients', schedules. The article concludes that direct observation, if used, should be flexible and convenient, whether at a health facility close to the patient's home or in the community. The emphasis should shift in practice from tablet watching towards treatment support, together with education and other adherence measures.

Computer-aided lung nodule detection in CT: results of large-scale observer test

RATIONALE AND OBJECTIVES

The objective is to study the incremental effects of using a computer-aided lung nodule detection (CAD) system on the performance of a large pool of observers.

MATERIALS AND METHODS

A set of eight thin-section computed tomographic data sets with limited longitudinal coverage, containing a total of 22 lung nodules, was analyzed by using the automated nodule detection system. When applied to all eight cases, the CAD system alone achieved a detection rate of 86.4%, with 2.64 false-positive results per case. This study included 202 observers at a national radiology meeting: 39 thoracic radiologists, 95 non-thoracic radiologists, and 68 non-radiologists. Each participant read from one to eight cases in random order, first without and then with CAD system output available. Observer performance in nodule detection was measured before and after CAD was made available. Differences in performance of groups of observers before and after CAD were tabulated by mean, median, and SD in detection rate and number of false-positive results and tested by using nonparametric methods.

RESULTS

In an analysis involving only the first randomly selected case read by all 202 participants, there were statistically significant increases in nodule detection rates and numbers of false-positive results for all types of observers. There was a significant difference in detection rates between radiologists and non-radiologists before CAD, but after CAD, there was no significant difference in detection rates between these observer types. In a second analysis involving 13 participants who read all eight cases, mean detection rates were 64.0% before CAD and 81.9% after CAD. Mean numbers of false-positive results were 0.144 per case before CAD and 0.173 after CAD.

CONCLUSION

In a large observer study, use of a CAD system for nodule detection resulted in an incremental increase in detection rate, but also led to an increase in number of false-positive results. Also, CAD appears to be an equalizer of detection rates between observers of different levels of experience.

Computer-aided diagnosis of the solitary pulmonary nodule

RATIONALE AND OBJECTIVES

We sought to investigate the utility of a computer-aided diagnosis in the task of differentiating malignant nodules from benign nodules based on single thin-section computed tomography image data.

MATERIALS AND METHODS

Eighty-one thin-section computed tomography data sets of solitary pulmonary nodules with proven diagnoses (48 malignant and 33 benign) were contoured manually on a single representative slice by a thoracic radiologist (>10 years of experience). Two separate contours were created for each nodule, one including only the solid portion of the nodule and one including any ground-glass components. For each contour 75 features were calculated that measured the attenuation, shape, and texture of the nodule. These features were than input into a feature selection step and four different classifiers to determine if the diagnosis could be predicted from the feature vector. Training and testing was conducted in a resubstitution and leave-one-out fashion and performance was evaluated using ROC techniques.

RESULTS

In a leave-one-out testing methodology the classifiers resulted with areas under the ROC curve (A(Z)) that ranged from 0.68 to 0.92. When evaluating with resubstitution the A(Z) ranged from 0.93 to 1.00.

CONCLUSION

Computer-aided diagnosis has the potential to assist radiologists in the task of differentiating solitary pulmonary nodules and in the management of these patients.

Solitary pulmonary nodule diagnosis on CT: results of an observer study

RATIONALE AND OBJECTIVES

To investigate the performance of observers with different levels of experience in distinguishing between benign and malignant solitary pulmonary nodules (SPN) on CT, and to determine the effects on interpretation of three different conditions: image data alone, the addition of clinical data, and the addition of output from a computer-aided diagnosis (CAD) system.

MATERIALS AND METHODS

28 thin-section CT datasets of SPNs with proven diagnoses (15 malignant and 13 benign) were used to measure observer performance. Readers were categorized according to their experience and read the cases in random order. For each case readers were asked to assign a level of confidence on a scale from 0.0-1.0 (0.0 benign, 1.0 malignant) for the diagnosis of the nodule. Each reader scored the cases based on review of image data alone (phase 1), then with limited clinical data (phase 2), and finally with CAD output (phase 3). To assess performance, multiple reader multiple case (MRMC) receiver operating characteristic (ROC) analysis was used.

RESULTS

2 thoracic radiologists, 1 thoracic radiology fellow, 2 nonthoracic radiologists, and 3 radiology residents read the cases. The average area under the ROC curve for all readers (A(z)) at each stage was 0.68, 0.75, and 0.81, for image data alone, with clinical data, and with CAD output respectively. The difference in performance between phases (2 and 3) and (1 and 3) was significantly different (P = 0.018 and P = 0.020). However, the difference between phases (1 and 2) was not significantly different (P = 0.155).

CONCLUSION

Diagnostic performance increased significantly with the addition of CAD output. With further validation CAD output may play a significant role in SPN management.

Database Design and Implementation for Quantitative Image Analysis Research

Quantitative image analysis (QIA) goes beyond subjective visual assessment to provide computer measurements of the image content, typically following image segmentation to identify anatomical regions of interest (ROIs). Commercially available picture archiving and communication systems focus on storage of image data. They are not well suited to efficient storage and mining of new types of quantitative data. In this paper, we present a system that integrates image segmentation, quantitation, and characterization with database and data mining facilities. The paper includes generic process and data models for QIA in medicine and describes their practical use. The data model is based upon the Digital Imaging and Communications in Medicine (DICOM) data hierarchy, which is augmented with tables to store segmentation results (ROIs) and quantitative data from multiple experiments. Data mining for statistical analysis of the quantitative data is described along with example queries. The database is implemented in PostgreSQL on a UNIX server. Database requirements and capabilities are illustrated through two quantitative imaging experiments related to lung cancer screening and assessment of emphysema lung disease. The system can manage the large amounts of quantitative data necessary for research, development, and deployment of computer-aided diagnosis tools.

Do private doctors follow national guidelines for managing pulmonary tuberculosis in Pakistan?

As private medical practitioners play a major role of in providing care to pulmonary tuberculosis (TB) patients, a survey was made of knowledge and practice in 2 cities in Pakistan. Only 1 of the 245 physicians was aware that cough > 3 weeks alone is the main symptom suggesting pulmonary TB. The majority diagnosed (80%) and treated (83%) cases themselves without referral. Less than 1% relied on sputum microscopy alone for diagnosis. None of the practitioners were following National TB Control guidelines for prescribing drugs and none ensured compliance with anti-TB treatment under supervision of a doctor/health worker. Only 3% kept records of pulmonary TB patients. None of the physicians assessed the effectiveness of treatment with sputum microscopy alone; the majority (76%) used only clinical assessment.

Gender perspectives on knowledge and practices regarding tuberculosis in urban and rural areas in Pakistan

We investigated gender differences in knowledge of and attitude towards tuberculosis (TB) in urban and rural communities in Sindh province, Pakistan. Knowledge of symptoms was generally deficient, particularly in rural females. Regarding TB prevention, 22.4% of rural and 14.4% of urban males said completing treatment was important; only 9.8% of rural and 7.1% of urban females agreed. Doctors were an important source of information in rural areas and 60.9% of rural males said they would only stop treatment on a doctor's advice. In contrast, > 65% of respondents in urban areas said they would stop treatment when symptoms ended. Our study highlights the need to increase population awareness about TB in Sindh.

Prospective evaluation of a new self-expanding plastic stent for inoperable esophageal strictures

BACKGROUND

High stent cost is considered the major drawback of self-expanding metal stents for dysphagia palliation in patients with inoperable esophageal strictures. We report our experience with a self-expanding plastic (Polyflex) stent, the cost of which is half that of the metal stents.

METHODS

Between September 1999 and April 2001, 16 dysphagic patients (15 men; mean age, 69.4 +/- 14.5 years; range, 49-100 years; mean dysphagia score, 3.31 +/- 0.6) with esophageal strictures who underwent Polyflex stent placement (insertion device diameter, 12-14 mm; postexpansion inner stent diameter, 16-21 mm; stent length, 9, 12, and 15 cm) were studied prospectively. The strictures were caused by postsurgical recurrence of gastric/esophageal cancer at the anastomotic site in five patients, primary esophageal cancer in four patients, esophagocardia junction cancer in four patients, metastatic mediastinal lymph nodes from a primary lung cancer invading the esophagus in 1 patient, and benign peptic stricture in two elderly patients. All the patients were prospectively followed until death.

RESULTS

Stent insertion was technically successful in 12 patients (75%). Stent placement failed in four patients (25%) because of failure to pass the delivery catheter across the stricture in three patients and failure of the stent to open in one patient. Early and late stent migration occurred in two patients and 1 patient, respectively. Tumor overgrowth occurred in 1 patient. The mean dysphagia score 7 days after stent placement was 1.1 +/- 0.9. Mean survival was 100.6 +/- 71.2 days (range, 8-225 days).

CONCLUSION

Self-expanding Polyflex stents are safe and effective for inoperable esophageal strictures and have an acceptable technical success rate. Further experience, better selection criteria, and design improvements should improve results.

Endoscopic treatment of extrahepatic bile duct strictures in patients with portal biliopathy carries a high risk of haemobilia: report of 3 cases

Extrahepatic portal venous obstruction can be associated with bile duct abnormalities, the entity being called portal biliopathy. Three cases are reported of extrahepatic bile duct strictures in patients with portal biliopathy who developed haemobilia during endotherapy. Although endoscopic therapy with stent placement can be successful in patients with portal biliopathy and could also lead to permanent stricture resolution, procedure-related haemobilia is not as uncommon as previously held. Shunt surgery could be a better option in fit patients, since it could provide definitive treatment in a young patient with an otherwise normal life expectancy.

Treatment of unresectable pancreatic carcinoma by intraluminal brachytherapy in the duct of Wirsung

BACKGROUND AND STUDY AIMS

Our aim was to evaluate the feasibility and clinical outcome of intraluminal brachytherapy (ILBT) in the duct of Wirsung in patients with unresectable pancreatic adenocarcinoma.

PATIENTS AND METHODS

Nine patients (eight men, one woman; mean age 72.4 +/- 9.1, range 52 - 80) with unresectable pancreatic adenocarcinoma of the head or body underwent ERCP for biliary and/or pancreatic stent placement and placement of a nasopancreatic drain with/without nasobiliary drain. The ILBT dose administered was 30 - 50 Gy calculated at 1 cm from the iridium-192 wire axis. Seven patients received ILBT from the duct of Wirsung whereas two patients received dual-duct ILBT (duct of Wirsung and the common bile duct). Three patients received combined-modality treatment (ILBT with external beam radiotherapy and 5-fluorouracil). The patients were prospectively followed up.

RESULTS

No endoscopy-related complications occurred. No radiation-related toxicity occurred in patients treated with ILBT alone. One patient undergoing combined-modality treatment developed gastric bleeding. Intraluminal source dislodgement occurred in three patients. Obvious tumor mass reduction of greater than 50 % was seen in three patients at 8 weeks after brachytherapy. Median survival was 11 months (range 6 - 37 months) and the 1-year and 3-year actuarial survival rates were 44 % and 15 %, respectively.

CONCLUSION

Intraluminal brachytherapy in the duct of Wirsung in patients with unresectable pancreatic carcinoma is safe and feasible. Further clinical trials are warranted.

Endoscopic palliation of unresectable malignant oesophageal strictures with self-expanding metal stents: comparing Ultraflex and Esophacoil stents

BACKGROUND

Two types of self-expanding metal stents to palliate dysphagia in patients with unresectable malignant oesophageal strictures have been compared.

METHODS

From February 1996 to October 2000, 50 metal stents (23 covered Ultraflex and 27 Esophacoil) were placed in 50 patients (40 males, mean age: 67+/-12 years, range: 33-100, mean dysphagia score: 3.18+/-0.66) with unresectable malignant oesophageal strictures. Patients were followed until death. A retrospective review has been made of a prospectively collected database.

RESULTS

The two groups were comparable as far as concerns degree of dysphagia, location and stricture length. Stent placement was successful in all cases. Covered Ultraflex stent was placed in 2 patients with oesophagobronchial fistula. No procedure-related deaths were seen. Early severe complications occurred in 2 patients (perforation in 1 and tumour bleeding in 1, in the Esophacoil group). Nine patients and 1 patient complained of pain following Esophacoil and Ultraflex stent placement, respectively. Late complications were asymptomatic rupture of distal Esophacoil rings in 2 patients, symptomatic Ultraflex stent migration in 2 and tumour overgrowth in 3 (Esophacoil 1, Ultraflex 2). Mean dysphagia score at 4 weeks after stent placement was 1.9+/-0.77. Mean survival was 177+/-109 days (range: 35-603 days). There were no significant differences in technical success, dysphagia palliation, complications (except chest pain) and survival using the two types of stent.

CONCLUSIONS

Self-expanding metal stents are safe with high technical success and achieve satisfactory long-term palliation for dysphagia. The covered Ultraflex and Esophacoil stents are equally effective.

Long-term follow-up of patients after endoscopic sphincterotomy for choledocholithiasis, and risk factors for recurrence

BACKGROUND AND STUDY AIMS

There have been growing concerns about the long-term sequelae of endoscopic sphincterotomy (ES). The aims of the study were to evaluate the long-term clinical outcome of ES for choledocholithiasis and to identify the predictors of recurrence.

PATIENTS AND METHODS

A total of 529 patients (233 men, 296 women; mean age 63, range 9 - 88) who underwent successful ES for choledocholithiasis were evaluated. Follow-up data were obtained retrospectively. Statistical analyses were carried out for 334 patients who had a follow-up of at least 5 years or had recurrence.

RESULTS

Immediate complications occurred in 37 patients (7 %). Follow-up data were available in 458 patients (86.6 %), of whom 280 (61.1 %) were asymptomatic, 127 (27.7 %) died from unrelated causes without recurrence, and 51 (11.1 %) had biliary symptoms and/or choledocholithiasis recurrence. Most recurrences (65 %) occurred more than 2 years following ES and were observed on multiple occasions in 13 patients (2.8 %). A bile duct diameter of 22 mm or greater was found to predict recurrence. Of 190 patients with an intact gallbladder, 11 (5.8 %) developed acute cholecystitis necessitating emergency cholecystectomy; all of these had previously documented gallstones.

CONCLUSIONS

Endoscopic sphincterotomy for choledocholithiasis is found to be safe at long-term follow-up. A dilated bile duct (> or = 22 mm) is a marker for patients at increased risk of recurrence of symptoms and/or choledocholithiasis.

Therapeutic biliary endoscopy

An analysis of the recent medical literature on therapeutic biliary endoscopy shows that the new millennium has already brought several significant developments. However, although advances continue rapidly, several new questions have also arisen, paving the way for further research. Several studies during the last year have also focused attention on cost-effectiveness.

Antagonists of the human CCR5 receptor as anti-HIV-1 agents. Part 3: a proposed pharmacophore model for 1-[N-(methyl)-N-(phenylsulfonyl)amino]-2-(phenyl)-4-[4-(substituted)piperidin-1-yl]butanes

Structure-activity relationship studies directed toward the optimization of (2S)-2-(3-chlorophenyl)-1-[N-(methyl)-N-(phenylsulfonyl)amino]-4-[4-(substituted)piperidin-1-yl]butanes as CCR5 antagonists resulted in the synthesis of the spiro-indanone derivative 8c (IC50=5 nM). These and previous results are summarized in a proposed pharmacophore model for this class of CCR5 antagonist.

Primary prophylaxis of variceal bleeding in liver cirrhosis: failure to learn from past experience

In patients with cirrhosis of liver, variceal bleeding is the most serious complication, with a mortality of up to 50%. Primary prophylaxis of variceal bleeding with shunt surgery or endoscopic variceal sclerotherapy was attempted and then abandoned, as higher rates of complications and mortality were observed. Endoscopic variceal ligation is now being recommended for primary prophylaxis in some centers, as it has fewer complications than sclerotherapy. But this has been done with inadequate evaluation of the cost-effectiveness of variceal ligation. Propranolol therapy is also being widely used for a selected group of patients (large varices with cherry red spots), despite its several limitations and side effects, to reduce frequency of bleeding but without improving survival. Is primary prophylaxis of variceal bleeding cost-effective? The cost involved needs to be accurately assessed in different countries.

Photodynamic therapy: a case series demonstrating its role in patients receiving mechanical ventilation

Photodynamic therapy (PDT) has long been used to treat cancers within the tracheobronchial tree. There have been many reports about the use of PDT for the treatment of carcinoma in situ and for obstructive endobronchial lesions. PDT has not been previously reported in patients receiving mechanical ventilation. PDT offers the advantages of a relatively short duration of treatment, a low side effect profile, and relatively low risk when compared to Nd-YAG laser in patients receiving mechanical ventilation. We report the first successful use of PDT to wean patients from mechanical ventilation.

Effect of cold pressor test and a high-chilli diet on rectosigmoid motility in irritable bowel syndrome

AIM

Visceral hypersensitivity characterizes the irritable bowel syndrome (IBS). We evaluated the effect of a cold pressor test (CPT)--hand immersion in ice water for 1 minute, which evokes a sympathetic response--on rectosigmoid motility in patients with IBS and normal volunteers. Since many Indian patients with IBS complain of worsening of symptoms following a spicy meal, we also evaluated whether a high-chilli diet affects symptoms or changes rectosigmoid motility.

METHODS

Fifteen men with IBS and 13 normal volunteers (all men) were studied. Baseline rectosigmoid manometry was done for 2 h, i.e., 1 h pre- and 1 h post-CPT. The subjects were then kept in hospital on a regular diet (approximately 5 g chilli daily) for 3 days, following which symptoms were reassessed and manometry repeated for 1 h. This was followed by a high-chilli diet (approximately 15 g/day) for 3 days, after which symptoms were reassessed and manometry repeated for 1 h.

RESULTS

There was no difference in the baseline study in the pre-CPT period between patients and control subjects. CPT did not change rectosigmoid motility in either group. IBS patients had varied effect on symptoms but no change in rectosigmoid motility after the high-chilli diet. In the normal volunteers, there was increased activity in the low rectum after the high-chilli diet.

CONCLUSIONS

Cold pressor test does not affect rectosigmoid motility in patients with IBS or normal subjects. A high-chilli diet has varied effect on symptoms in patients with IBS and does not affect rectosigmoid motility.

Substituted 2-aminopyridines as inhibitors of nitric oxide synthases

A series of substituted 2-aminopyridines was prepared and evaluated as inhibitors of human nitric oxide synthases (NOS). 4,6-Disubstitution enhanced both potency and specificity for the inducible NOS with the most potent compound having an IC50 of 28 nM.

Effect of acute and long-term oral tobacco use on oesophageal motility

BACKGROUND AND AIMS

Nicotine administration is known to decrease lower oesophageal sphincter (LOS) pressure. Although a few studies have assessed the effect of tobacco on the LOS, the effect of acute and long-term oral tobacco use on oesophageal motility is not known. The study was designed to investigate the effect of acute and long-term oral tobacco use on LOS and distal oesophageal motility.

METHODS

Thirty-six healthy men (aged 18-65 years, median 34 years; 18 oral tobacco users, 18 non-tobacco users) underwent oesophageal manometry using a water-perfusion system. After baseline manometry, tobacco users were asked to keep 0.5 g tobacco in their mouth for 10 min; non-users of tobacco were kept in quiet surroundings for a similar period. Manometry was then repeated.

RESULTS

The LOS basal pressures were similar in tobacco users and non-tobacco users (mean +/- SD 15.4 +/- 6.3 vs 13.4 +/- 5.3 mmHg). In the distal oesophageal body, the velocity (4.4 +/- 3.1 vs 4.9 +/- 2.6 cm/s), amplitude (92.7 +/- 38.3 vs 84.8 +/- 33.2 mmHg) and duration of contraction (2.1 +/- 0.7 vs 1.7 +/- 0.9 s) were similar in tobacco users and non-users. Acute tobacco use did not affect these parameters. The numbers of abnormal waves (triple peaks and non-transmitted contractions) were also similar in the two groups.

CONCLUSION

Oral tobacco use does not appear to affect LOS pressures and distal oesophageal motility acutely or in the long term.

Jejunal stricture complicating acute mesenteric venous thrombosis secondary to protein C deficiency and factor V Leiden gene mutation

We report a patient with high small intestinal obstruction due to ischemic stricture, secondary to acute mesenteric venous thrombosis. Tests done for hypercoagulability revealed dual etiology (protein C deficiency and factor V Leiden gene mutation). The patient underwent surgical resection and has been on anticoagulation treatment. At 2 years' follow up, she remains asymptomatic.

Acute lymphoblastic leukemia presenting with severe jaundice in an adult

We report an adult patient of acute lymphoblastic leukemia presenting with liver dysfunction.

L-tryptophan urea amides as NK1/NK2 dual antagonists

We report that a systematic modification of an NK1 receptor selective antagonist resulted in the identification of novel compounds, 4c and 4d, with high affinity for both NK1 and NK2 receptors.

Structural requirements for human inducible nitric oxide synthase substrates and substrate analogue inhibitors

Inducible nitric oxide synthase (iNOS; EC 1.14.13.39) catalyzes the NADPH-dependent oxidation of one of the free guanidino nitrogens of L-Arg to form nitric oxide and L-citrulline. Analogues of L-Arg and the inhibitor, L-N6-(1-iminoethyl)lysine, were used to define structural elements required for the binding and catalysis of compounds. L-Arg analogues with sequentially shorter methylene spacing between the guanidino group and the amino acid portion of the molecule were not iNOS substrates but were reversible inhibitors. L-Arg analogues such as agmatine with a hydroxyl substitution at the 2-amino position were substrates. Desaminoarginine was not a substrate but a reversible inhibitor. Desaminoarginine, agmatine, and argininic acid bound to the enzyme to give type I difference spectra similar to that of L-Arg. The amidino compounds L-N6-(1-iminoethyl)lysine, L-N5-(1-iminoethyl)ornithine, and N5-(1-iminoethyl)cadaverdine, but not N6-(1-iminoethyl)-6-aminocaproic acid, were NADPH-dependent, irreversible inactivators of iNOS. For both the L-Arg and L-N6-(1-iminoethyl)lysine analogues, the 2-amino group appeared to play an important role in catalytic events leading to either substrate turnover or mechanism-based inactivation. Inactivation of iNOS by L-N6-(1-iminoethyl)lysine was NADPH- and dioxygen-dependent, but low incorporation of radiolabel with DL--4, 5-3H]-N6-(1-iminoethyl)lysine indicates that the mechanism of enzyme inactivation is not covalent modification of the protein.

Prevalence of hepatitis C virus (HCV) infection in Mumbai

A study was carried out to determine the prevalence of Hepatitis C virus (HCV) in Mumbai among certain high risk groups such as renal transplant recipients, multitransfused and haemodialysis patients; professional and voluntary blood donors and viral hepatitis cases for comparison. Repeated testing of 602 subjects for antibodies to HCV using a second generation ELISA assay (Abbott, USA) showed an overall prevalence of 16.9%. We found 36.4% of multitransfused patients, 27.8% of renal failure cases and 26.2% of renal transplant recipients to be seropositive. Voluntary blood donors in our series showed a surprisingly high prevalence of 15.9%, and this group needs further investigation. Fifty-six of these sera (of which 45 were anti-HCV positive) were tested for HCV RNA by PCR and 14(31.1%) of the seropositive samples were also HCV RNA positive. The present investigation not only shows a high prevalence of HCV in the study groups but also proves the presence of HCV genomes in a significant proportion.

Identification of nitric oxide synthase as a protective locus against tuberculosis

Mutagenesis of the host immune system has helped identify response pathways necessary to combat tuberculosis. Several such pathways may function as activators of a common protective gene: inducible nitric oxide synthase (NOS2). Here we provide direct evidence for this gene controlling primary Mycobacterium tuberculosis infection using mice homozygous for a disrupted NOS2 allele. NOS2(-/-) mice proved highly susceptible, resembling wild-type littermates immunosuppressed by high-dose glucocorticoids, and allowed Mycobacterium tuberculosis to replicate faster in the lungs than reported for other gene-deficient hosts. Susceptibility appeared to be independent of the only known naturally inherited antimicrobial locus, NRAMP1. Progression of chronic tuberculosis in wild-type mice was accelerated by specifically inhibiting NOS2 via administration of N6-(1-iminoethyl)-L-lysine. Together these findings identify NOS2 as a critical host gene for tuberculostasis.

Mechanism of inhibition of human leucocyte elastase by beta-lactams. 3. Use of electrospray ionization mass spectrometry and two-dimensional NMR techniques to identify beta-lactam-derived E-I complexes

A combination of NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS) was used to probe the identity of beta-lactam-derived complexes with serine proteases. The carbon and proton NMR chemical shifts of the human leucocyte elastase (HLE)-inhibitor complex derived from [4-13C]-L-680,833, [S-(R*,S*)]-4-[(1-(((1-(4- methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-oxo-4- azetidinyl)oxy]benzeneacetic acid, were consistent with an sp3 hybridized carbon. The ESI-MS spectrum of the L-680,833-derived HLE-I complex indicated an increase of 333 Da over the mass of the free enzyme. The data are consistent with acylation of the active site serine, loss of p-hydroxybenzeneacetic acid, and formation of a carbinolamine at the carbon deriving from C-4 of the lactam ring. The complexes produced from HLE and the diastereomers of L-680,833 display identical masses. Since the 4R-isomers produce more stable complexes [Green et al. (1995) Biochemistry 34, 14331-14343], these data suggest that these complexes differ in their stereochemistry or conformation. The structural model of the HLE-I complexes derived from the diastereomers predicts that the hydroxyl of the carbinolamine derives from a structurally observed water molecule yielding S-stereochemistry in all cases. In this model, the 4S- and 4R-diastereomers produce complexes that differ by the location of the side chain of a phenylalanine residue. The mass of HLE was increased by that of L-684,481, (R)-1-(((1-(4-methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-azetidino ne, which lacks a leaving group at C-4 in the complex derived from this compound. L-691,886, [S-(R*,S*)]-4-[(1-(((1-(4-ethoxyphenyl)butyl)amino)carbonyl)- 3,3-diethyl-4-oxo-2-azetidinyl)-oxy]benzeneacetic acid, produces two complexes of different mass that reactivate with different rates. The mass of the less stable complex is consistent with the acyl-enzyme of 2,2-ethyl-3-oxopropanoic acid while the mass of the more stable complex is analogous to the carbinolamine observed during L-680,833 inactivation. Porcine pancreatic elastase (PPE) produces a complex with a mass consistent with replacement of the C-4 leaving group by water to produce a carbinolamine from L-684,248, [S-(R*,S*)]-4-[(1-(((1-(4-methylphenyl)butyl)amino)carbonyl)-3,3-dimethy l - 2-oxo-4-azetidinyl)oxy]benzoic acid. The C-4 diastereomer, L-684,249, produces two PPE-I complexes with different masses. One of these complexes has a mass identical to the mass of the complex derived from L-684,248 while the mass of the other complex indicates the presence of the entire inhibitor molecule.(ABSTRACT TRUNCATED AT 400 WORDS)

Mechanism of inhibition of human leucocyte elastase by beta-lactams. 2. Stability, reactivation kinetics, and products of beta-lactam-derived E-I complexes

The monocyclic beta-lactams reported by Knight et al. [Knight, W. B., et al. (1992) Biochemistry 31, 8160; Chabin, R., et al. (1993) Biochemistry 32, 8970] as inhibitors of human leucocyte elastase (HLE) produce stable HLE-inhibitor complexes that slowly reactivate with half-lives ranging from less than 1 to 15 h at 37 degrees C. The complexes produced between PPE and two C-3 dimethyl-substituted beta-lactams are less stable than those produced between HLE and analogous C-3 diethyl-substituted lactams. The stability of the HLE-I complexes is governed primarily by the structure of the substituted urea portion of the inhibitors and not by the identity or presence of a leaving group at C-4 of the lactam ring. In some cases substitutions on the urea portion of the inhibitors yielded complexes that displayed biphasic reactivation kinetics. This suggests the presence of at least two different complexes. The stereochemistry of the leaving group at C-4 has a small effect on the stability of the final complex (1.3-2-fold); therefore, the identity of the final complex is dependent upon the initial stereochemistry at that position. The stability of the complexes was relatively insensitive to hydroxylamine, which suggests that the acyl-enzymes are protected from nucleophilic "rescue". The rate of reactivation of the complex derived from L-680,833,[S-R*,S*)]-4-[(1-(((1-(4- methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-oxo-4-azetidinyl)ben zeneacetic acid, was pH independent, while the L-684,481, (R)-(1-(((1-(4-methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-azeti din one generated complex displayed a pH-dependent reactivation rate. In the latter case, the increase in reactivation rate with pH displayed a pKa of 7.2. This is consistent with the requirement for base catalysis by the active site histidine to regenerate enzymatic activity. Reactivation of the L-680,833-derived complex produced different products as a function of pH, suggesting two different pH-dependent routes of reactivation. At low pH a route that produced primarily the substituted urea is favored, while at higher pH production of two six-membered ring diastereomers competes with urea generation. Thus, the apparent pH independence of the return of activity is the result of two offsetting pathways. Other compounds such as L-670,258, (S)-4-[((((2-naphthylmethyl)amino)carbonyl)-3,3-diethyl-4-oxo-2- azetidinyl)oxy]benzoic acid, reactivate by these two routes as well as by aminolysis by the other urea nitrogen to produce an additional regioisomer. The temperature dependence of the reactivation of the complexes derived from L-684,481 and L-680,833 suggests different mechanisms.(ABSTRACT TRUNCATED AT 400 WORDS)

An inhibitor of leukocyte elastase prevents immune complex-mediated hemorrhage in the rat lung

The typical reverse passive Arthus reaction (RPA) was attained in rats by the instillation of a rabbit antiovalbumin serum into the lungs and intravenous injection of ovalbumin. Instillation of antiserum alone caused accumulation of polymorphonuclear leukocytes (PMN) and increased vascular permeability, but did not cause hemorrhage. However, when an intravenous injection of ovalbumin was also given, the vascular permeability of the lungs increased dramatically and PMN, as well as hemoglobin, were measurable in the lung lavage fluids by 4 hr after initiation of the reaction. Various proteinase inhibitors were instilled into the lungs after the initial stages of the RPA had developed, specifically to investigate their effect on the development of the hemorrhage, which we chose to monitor as an indicator of severe vascular damage. A cephalosporin-based beta-lactam, L-658,758, which is a time-dependent inhibitor of human and rat PMN elastase, effectively prevented the lung hemorrhage associated with the RPA reaction (ED50 = 2 x 55 micrograms doses/animal when instilled at 1.5 and 2.5 hr after initiating the RPA). The PMN elastase inhibitor, methoxysuccinyl-alanyl-alanyl-prolyl-valine-chloromethylketone, also inhibited hemorrhage in this model. Compounds of the same chemical class as these elastase inhibitors, but having no activity against PMN elastase in vitro, did not affect the hemorrhage associated with the RPA. Several specific inhibitors of proteinases other than PMN elastase (e.g., pepstatin and methoxysuccinyl-prolyl-glycyl-alanyl-lysine-chloromethylketone) were found to have little effect on the hemorrhage associated with the RPA reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Orally active beta-lactam inhibitors of human leukocyte elastase. 3. Stereospecific synthesis and structure-activity relationships for 3,3-dialkylazetidin-2-ones

The stereospecific synthesis of several 4-[(4-carboxyphenyl)oxy]- 3,3-dialkyl-1-[[(1-phenylalkyl)-amino]carbonyl]azetidin-2-on es 3 is described in which the C-3 alkyl groups were varied from methyl to butyl as well as allyl, benzyl and methoxymethyl. The structure-activity relations for these compounds are discussed in terms of the hydrolytic stability of the beta-lactam ring, their in vitro inhibitory potency for human leukocyte elastase (HLE), and their in vivo oral efficacy in an HLE-mediated hamster lung hemorrhage assay. Further alkyl substitution on the benzylic urea moiety, especially in the R configuration, afforded enhanced HLE inhibition and in vivo efficacy. The stereochemical assignments for (3R,4S)-4-[(4-carboxyphenyl)oxy]-3-ethyl-3-methyl-1-[[((R)-1- phenylpropyl)amino]carbonyl]azetidin-2-one (42a) (kobs/[I] = 91,000 M-1 s-1) were confirmed with an X-ray structure determination, which was also utilized to develop an HLE inhibition model.

Determination of the kinetic parameters of Escherichia coli leader peptidase activity using a continuous assay: the pH dependence and time-dependent inhibition by beta-lactams are consistent with a novel serine protease mechanism

Bacterial leader peptidase (LPase) is a potential target for the development of novel anti-infective agents, but to data only peptides based upon natural macromolecular substrates have been reported as inhibitors. In this work is described a continuous assay for Escherichia coli LPase activity, based upon Ac-WSASALAKI-AMC (I) as the substrate, that can be monitored either spectrophotometrically or spectrofluorometrically. The LPase reaction is coupled to the liberation of AMC (aminomethylcoumarin) via a nonspecific leucine aminopeptidase. LPase and a short form of the enzyme (LPase-sf) lacking the membrane spanning domains displayed saturable kinetics toward I. The second-order rate constants were approximately 2 x 10(5) M-1 h-1 at pH 7.5 and were comparable to those reported in the literature for peptide substrates based upon natural cleavage sites in preproteins. LPase was inhibited by beta-lactams. [S-(R*,S*)]-4-[(1-(((1-(5-toluoyl)butyl)amino)carbonyl)-3,3-dimethyl-4- oxo-2-azetidinyl)oxyl]benzoic acid (L-684,-248, 588 microM) inhibited the LPase-catalyzed hydrolysis of 50 microM I and 125 microM Ac-WLVP-Nleu-LSFAAEGDDPA-NH2 by 30% and 88% over 1 and 4 h, respectively. The inhibition of LPase by L-684,248 and its C-4 diasteromer was time dependent and yielded second-order rate constants (kinact/Ki) of 12 and 7.7 M-1 min-1, respectively. The process was structurally specific as the C-3 diethyl substituted beta-lactam (C-4 S-isomer) was inactive. The latter data correlate with the LPase preference for alanine at the P1 position of peptide substrates [Kuo et al. (1993) Arch. Biochem. Biophys. 303, 274-280].(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical, biochemical, pharmacokinetic, and biological properties of L-680,833: a potent, orally active monocyclic beta-lactam inhibitor of human polymorphonuclear leukocyte elastase

A series of potent and highly selective time-dependent monocyclic beta-lactam inhibitors of human polymorphonuclear leukocyte elastase (PMNE, EC 3.4.21.37) is described. The intrinsic potency of these compounds, as exemplified by L-680,833 (k(inactivation)/K(i) of 622,000 M-1.s-1), is reflected at the cellular level where it inhibits generation of the specific N-terminal cleavage product A alpha-(1-21) from the A alpha chain of fibrinogen by enzyme released from isolated polymorphonuclear leukocytes stimulated with fMet-Leu-Phe with an IC50 of 0.06 microM. The inhibitory activity of L-680,833 is also apparent in whole blood stimulated with A23187, where it inhibits formation of A alpha-(1-21) and PMNE-alpha 1-proteinase inhibitor complex formation with IC50 values of 9 microM. Pharmacokinetic studies indicate that after oral dosing L-680,833 is bioavailable in rats and rhesus monkeys. This oral bioavailability is reflected by the inhibition (i) of tissue damage elicited in hamster lungs by intratracheal instillation of human PMNE and (ii) enzyme released from human PMN stimulated after their transfer into the pleural cavity of mice. The properties of L-680,833 allow it to effectively supplement the activity of natural inhibitors of PMNE in vivo, suggesting that this type of low-molecular-weight synthetic inhibitor could have therapeutic value in diseases where PMNE damages tissue.

Painless legs and moving toes: a syndrome related to painful legs and moving toes?

The syndrome of painful legs and moving toes consists of continuous or semicontinuous involuntary writhing movements of the toes associated with pain in the affected extremity. We report a 57-year-old man with a 33-year history of painless and semicontinuous involuntary movements of the toes of the left foot similar to those seen in painful legs and moving toes. There was no family history of movement disorder. The history and physical examination were negative for significant trauma, radiculopathy, or peripheral neuropathy. There were no other neurological findings or involuntary movements. It is unlikely that the involuntary movements were precipitated by neuroleptics or psychosis. CT scan of the head; EEG, CT, and MRI scans of the lumbosacral spine; and EMG and nerve conduction studies of the legs showed no significant abnormalities except for a predominant cocontraction of the left foot flexors and extensors at 0.6-1.2 Hz in a pattern sometimes seen in painful legs and moving toes. We conclude that there is a condition clinically and electrophysiologically similar to painful legs and moving toes that we call painless legs and moving toes, the etiology of which remains undetermined.

Orally active beta-lactam inhibitors of human leukocyte elastase. 2. Effect of C-4 substitution

The effect of changing the C-4 substituent of 3,3-diethyl-1-[(benzylamino)carbonyl]-2-azetidinone on inhibition of HLE and in a model of HLE-induced lung damage in hamsters was explored. Substituents at this position do not appear to interact strongly with HLE with the most potent compounds having k(obs)/[I] = 6900 M-1 s-1. However, substituents at this position had a marked effect on in vivo activity. The greatest oral activity in the lung hemorrhage assay was achieved with C-4 aryl carboxylic acid ethers (60-85% inhibition at 30 mg/kg po). Based upon the established mechanism of inhibition by these compounds, the C-4 substituent would be released, and therefore, the pharmacological potential of these C-4 substituents was of considerable concern. Fortunately, compounds containing 4-hydroxybenzoic acid and 4-hydroxyphenylacetic acid ethers at C-4 were among the most active analogs. These phenolic acids are also found as urinary metabolites in healthy humans. Other heteroaryls at C-4 were also orally active in this model despite relatively modest enzyme activity.

Orally active beta-lactam inhibitors of human leukocyte elastase-1. Activity of 3,3-diethyl-2-azetidinones

A thorough analysis of the mechanism of inhibition of human leukocyte elastase (HLE) by a monocyclic beta-lactam and the mechanism of beta-lactam hydrolysis led to the preparation of potent and highly stable inhibitors of HLE. This work led to the identification of 4-[(4-carboxyphenyl)-oxy]-3,3-diethyl-1- [[(phenylmethyl)amino]carbonyl]-2-azetidinone (2) as the first orally active inhibitor of human leukocyte elastase (HLE). Analogs of 2 with different substituents on the urea N were synthesized and evaluated for their activity in vitro against HLE as well as in vivo in a hamster lung hemorrhage model. Compounds with a methyl or a methoxy group in the para position of the benzene ring were very potent in both assays. The results are discussed on the basis of the proposed model for the binding of this class of inhibitors to HLE and a possible mechanism of inhibition is presented.

Inhibition of human leukocyte elastase. 4. Selection of a substituted cephalosporin (L-658,758) as a topical aerosol

Human leukocyte elastase (HLE) is a serine protease which has been implicated as a causative agent in several pulmonary diseases. The continued modification of our previously reported cephalosporin-based HLE inhibitors has led to the identification of a series of C-2 amides with potent, topical activity in an in vivo hamster lung hemorrhage model. While the most potent in vitro HLE inhibition had previously been obtained with lipophilic ester derivatives, it was found that the less active, but more polar and stable, amide derivatives were much more effective in vivo. The development of the structure--activity relations for optimization of these activities is discussed. These results led to the selection of 3-(acetoxymethyl)-2-[(2(S)-carboxypyrrolidino)carbonyl]-7 alpha-methoxy-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene, 5,5-dioxide (3, L-658,758) as a selective, potent, time-dependent HLE inhibitor suitable for formulation as a topical aerosol drug for possible clinical use.

Mechanism of inhibition of human leukocyte elastase by two cephalosporin derivatives

The cephalosporin derivatives L 658758 [1-[[3-(acetoxymethyl)-7 alpha-methoxy-8-oxo-5-thia-1-azabicyclo [4.2.0]oct-2-en-2-yl]carbonyl]proline S,S-dioxide] and L 659286 [1-[[7 alpha-methoxy-8-oxo-3-[[(1,2,5,6-tetrahydro-2-methyl-5,6-dioxo- 1,2,4-triazin-3-yl)thio]methyl]-5-thia-1-aza-(6R)-bicyclo[4.2.0]-o ct-2-en-2-yl]carbonyl]pyrrolidine S,S-dioxide] are mechanism based inhibitors of human leukocyte elastase (HLE). The mechanism involves initial formation of a Michaelis complex followed by acylation of the active site serine. The group on the 3'-methylene is liberated during the course of these reactions, followed by partitioning of an intermediate between hydrolysis to regenerate active enzyme and further modification to produce a stable HLE-inhibitor complex. The partition ratio of 2.0 obtained for the reaction with L 658758 approaches that of an optimal inhibitor. These compounds are functionally irreversible inhibitors as the recovery of activity after inactivation is slow. The half-lives at 37 degrees C of the L 658758 and L 659286 derived HLE-I complexes were 9 and 6.5 h, respectively. The complexes produced by both inhibitors are similar chemically since the thermodynamic parameters for activation to regenerate active enzyme are essentially identical. The free energy of activation for this process is dominated primarily by the enthalpy term. The stability of the final complexes likely arises from Michael addition on the active site histidine to the 3'-methylene.

Inhibition of human leukocyte elastase. 3. Synthesis and activity of 3'-substituted cephalosporins

Several 3'-substituted cephalosporin sulfones were synthesized from 3-(hydroxymethyl)cephalosporin, which was prepared by Ti(OiPr)4 hydrolysis of the corresponding acetate. A method was also developed to prepare a 3-vinylcephalosporin. Some of these compound were found to be potent time-dependent inhibitors of human leukocyte elastase (HLE). The HLE inhibitory activity was correlated with sigma 1 and it was concluded that the potency was determined by the electron-withdrawing ability as well as the size of the substituent. A mechanism for inhibition of HLE by cephalosporin sulfones is proposed.

Inhibition of human leukocyte elastase. 2. Inhibition by substituted cephalosporin esters and amides

A variety of 7 alpha-methoxycephalosporin ester and amide sulfones were prepared and tested to determine the structure-activity relations for inhibition of human leukocyte elastase (HLE), a serine protease which has been implicated in several degenerative lung and tissue diseases. The most potent IC50 values were obtained with neutral, lipophilic derivatives, with the esters being more active than the amides. However, the best time-dependent inhibition in this series was observed with the p- and m-carboxybenzyl esters 7b and 7c. These results are discussed in terms of the proposed mechanism of inhibition as well as a molecular modeling study using the recently solved X-ray crystal structure of HLE.

Laparoscopic retrieval of transmigrated IUDS (report of 3 cases)

Three cases in whom transmigrated IUDs were removed with operative laparoscope are presented.

Admissions, patterns of utilization and disposition of cases of acute stroke in Brisbane hospitals

In a population of slightly-more than one million persons, all cases of acute admission to hospital for cerebrovascular disease during 1984 were studied. Of the 2676 hospital admissions, 91% were of public-hospital patients. Of the 1908 patients who were aged more than 25 years and whose conditions were assigned the International classification of diseases' (ICD-9) codes (430-437) for cerebrovascular accidents, 1264 (1.8 patients per 1000 population of older than 25 years of age) cases were completed strokes, and 644 (1.0 patients per 1000 population of older than 25 years of age) cases were transient ischaemic attacks. There was no significant difference between the specific aetiological types of stroke that were diagnosed neuroradiologically and those that were diagnosed clinically. Among the cases of completed strokes, 54% of cases were thrombotic, 11% of cases were embolic, and 15% of cases were haemorrhagic, while nearly 20% of cases were unclassified. Twenty-one per cent of patients who were admitted to hospital with completed strokes died within two weeks of their admission, 28% of such patients were discharged home, 8% of such patients were transferred to full-maintenance care, and the remaining 43% of such patients were transferred for inpatient rehabilitation. The median length of stay for patients with completed strokes was 11.8 days compared with 6.2 days for patients with transient ischaemic attacks.

Factors affecting performance of Nili-Ravi buffaloes in Pakistan

Effects of herd, year, age, season, and lactation length on milk yield and reproductive efficiency for the Nili-Ravi breed of buffalo were determined by analysis of variance of 5,716 lactation records from two herds in Pakistan. Herds differed in all traits. Herd average milk yields were 1,702 and 2,064 kg. Year, season, herd, parity number, days in milk, days open, age, and sire all influenced milk yield. Herd, year, season, and parity number also had significant effects on days open and calving interval. Month of calving was important for time until return to estrus. Percentages of variance in milk yield attributed to herd, year, sire, cow, and residual were 20.3, 11.4, 4.3, 17.0, and 47.0. Classification of lactation length (greater than 60, greater than 250, or at least 305 days) markedly influenced the sire component of variance suggesting some interdependence of milk yield and lactation length. Total variance for milk yield was 466,911 kg2. Within herd heritability for milk yield was .25, and repeatability was low (.31). Predicted breeding values for sires for 250 to 305-day milk ranged from -172 kg to +260. Cows in Herd 1 completed 5.58 lactations with an average herd life of 12.3 yr; Herd 2 cows completed 4.52 lactations with culling at 10.6 yr. Frequency of termination of lactations because of mastitis, reproductive problems, or health was similar to frequencies for cattle. Factors affecting milk yield in buffaloes are similar to those of cattle.

Factors affecting milk fat percent of Nili-Ravi buffaloes in Pakistan

Monthly fat tests for 895 lactations of Nili-Ravi buffaloes in a Livestock Production Research Institute herd were used to estimate environmental effects on fat percentage. Fat tests rose progressively from 1st to 10th mo of lactation (5.51 to 7.46%). Average lactation fat percent was 6.55 +/- .06. Year effects were significant, but season, age, parity, milk yield, and health status were not. Percent fat increased slightly to maturity (6.54 first parity; 6.65 fifth). Lactations initiated April to September averaged slightly higher (6.60%) than other months (6.50%). There was a slight, although real, decrease in fat percent with increased lactation milk yield (6.60, 6.63, 6.60, 6.43, 6.51 for 1000 to 1500, 1501 to 2000, 2001 to 2500, 2501 to 3000, and greater than 3,000 kg). Effect of treatment for health problems was small (6.51 treated versus 6.59% untreated). Of all fat tests (7,772) 60% were 5.1 to 7.0%, 27% were between 7 and 9%, but only 3% exceeded 9%. Lactation fat percent averaged 1.0 less than most percents for buffaloes because of system of milking and milk yield (2,130 kg). Fat percentage of buffaloes appears to be influenced by environmental factors in the same proportion as for cattle, but buffaloes would be expected to exceed cattle in fat percent by 1 to 3% depending on breed and environmental conditions.